Systems and methods for out of aisle localization and vehicle position calibration using rack leg identification

ABSTRACT

A materials handling vehicle includes a camera, odometry module, processor, and drive mechanism. The camera captures images of an identifier for a racking system aisle and a rack leg portion in the aisle. The processor uses the identifier to generate information indicative of an initial rack leg position and rack leg spacing in the aisle, generate an initial vehicle position using the initial rack leg position, generate a vehicle odometry-based position using odometry data and the initial vehicle position, detect a subsequent rack leg using a captured image, correlate the detected subsequent rack leg with an expected vehicle position using rack leg spacing, generate an odometry error signal based on a difference between the positions, and update the vehicle odometry-based position using the odometry error signal and/or generated mast sway compensation to use for end of aisle protection and/or in/out of aisle localization.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 62/801,893, entitled “SYSTEMS AND METHODS FOR VEHICLE POSITIONCALIBRATION USING RACK LEG IDENTIFICATION AND MAST SWAY COMPENSATION,”filed Feb. 6, 2019; U.S. Provisional Application Ser. No. 62/801,897,entitled “SYSTEMS AND METHODS FOR END OF AISLE PROTECTION AND VEHICLEPOSITION CALIBRATION USING RACK LEG IDENTIFICATION,” filed Feb. 6, 2019;and U.S. Provisional Application Ser. No. 62/801,904, entitled “SYSTEMSAND METHODS FOR OUT OF AISLE LOCALIZATION AND VEHICLE POSITIONCALIBRATION USING RACK LEG IDENTIFICATION,” filed Feb. 6, 2019, theentireties of which are incorporated by referenced herein.

TECHNICAL FIELD

The present specification generally relates to systems and methods forproviding and updating localization for industrial vehicles based on aracking system in a warehouse environment and, more specifically, tosystems and methods for utilization of a rack leg imaging module on anindustrial vehicle and upright rack leg rails of the racking system totrack and update the location of the industrial vehicle in an aisle ofthe warehouse based on a rack leg identification associated with theaisle.

BACKGROUND

In order to move items about an industrial environment, workers oftenutilize industrial vehicles, including for example, forklift trucks,hand and motor driven pallet trucks, and/or other materials handlingvehicles. The industrial vehicles can be configured as an automatedguided vehicle that navigates through the industrial environment or amanually guided vehicle that knows its location within the industrialenvironment. In order to facilitate automated guidance, navigation, orboth, the industrial vehicle may be adapted for localization within theenvironment. That is the industrial vehicle can be adapted with sensorsand processors for determining the location of the industrial vehiclewithin the environment such as, for example, pose and position of theindustrial vehicle.

BRIEF SUMMARY

According to the subject matter of the present disclosure, in a firstaspect, a materials handling vehicle comprises a camera, a mastassembly, a mast assembly control unit, a fork carriage assembly, avehicle position processor, and a drive mechanism configured to move thematerials handling vehicle along an inventory transit surface of awarehouse, and the mast assembly and the mast assembly control unit areconfigured to move the fork carriage assembly along a vertical liftaxis. The camera is secured to the fork carriage assembly and isconfigured to capture (i) a forks down image of at least a portion of arack leg positioned in a racking system aisle of the multilevelwarehouse racking system, and (ii) a forks-up image of at least aportion of a rack leg positioned in a racking system aisle of themultilevel warehouse racking system. The vehicle position processor isconfigured to generate a forks-down coordinate X1 of the camera along ahorizontal axis from the forks-down image of the rack leg, generate aforks-up coordinate X2 of the camera along a horizontal axis from aforks-up image of the rack leg captured with the fork carriage assemblyat a lift height H1, determine a mast sway offset as a differencebetween the forks-down coordinate X1 and the forks-up coordinate X2, anddetermine a horizontally advanced position of the materials handlingvehicle with the fork carriage assembly at the lift height H1 using themast sway offset and a subsequently captured forks-up image of at leasta portion of a rack leg positioned in the racking system aisle.

In a second aspect, comprising the materials handling vehicle of thefirst aspect, the camera is further configured to capture an image of anaisle entry identifier in a multilevel warehouse racking system, and thevehicle position processor is further configured to generateaisle-specific rack leg spacing data from an image of an aisle entryidentifier, as captured by the camera, and determine the horizontallyadvanced position of the materials handling vehicle with the forkcarriage assembly at the lift height H1 using the aisle-specific rackleg spacing data in addition to the mast sway offset and thesubsequently captured forks-up image.

In a third aspect, comprising the materials handling vehicle of firstaspect or the second aspect, the camera is further configured to capturean image of an aisle entry identifier in a multilevel warehouse rackingsystem, and the vehicle position processor is further configured togenerate end-of-aisle positional data and aisle-specific rack legspacing data from an image of an aisle entry identifier, as captured bythe camera, and generate an initial position of the materials handlingvehicle along the inventory transit surface using the end-of-aislepositional data. The vehicle position processor is further configured togenerate an expected position of the materials handling vehicle as thevehicle travels down a racking system aisle corresponding to the aisleentry identifier from the end-of-aisle positional data, theaisle-specific rack leg spacing data, and a forks-down image of at leasta portion of a rack leg positioned in the racking system aisle, andupdate the expected position of the materials handling vehicle as thevehicle travels down the racking system aisle using the mast sway offsetand the subsequently captured forks-up image of at least a portion of arack leg positioned in the racking system aisle.

In a fourth aspect, comprising the materials handling vehicle of thethird aspect, the aisle entry identifier is disposed on an end rack legof the racking system aisle.

In a fifth aspect, comprising the materials handling vehicle of any ofthe first aspect to the fourth aspect, the camera is secured directly orindirectly to the fork carriage assembly.

In a sixth aspect, comprising the materials handling vehicle of any ofthe first aspect to the fifth aspect, the camera is further configuredto capture an image of an aisle end identifier in a multilevel warehouseracking system, and the vehicle position processor is further configuredto generate end-of-aisle limit data comprising an end-of-aisle limitfrom an image of an aisle end identifier, as captured by the camera,determine whether the materials handling vehicle exceeds theend-of-aisle limit, transmit a limit-based command to the drivemechanism of the materials handling vehicle when an operating state ofthe materials handling vehicle exceeds the end-of-aisle limit, initiatea vehicle action based on the limit-based command, the vehicle actionconfigured to modify operation of the materials handling vehicle to amodified operating state within the end-of-aisle limit, and navigate thematerials handling vehicle to exit the racking system aisle in themodified operating state.

In a seventh aspect, comprising the materials handling vehicle of thesixth aspect, the aisle end identifier is disposed on an aisle end rackleg.

In an eighth aspect, comprising the materials handling vehicle of thesixth aspect, the end-of-aisle limit comprises a speed limit, a liftheight limit, an acceleration limit, a deceleration limit, a liftacceleration limit, a lift deceleration limit, or combinations thereof.

In a ninth aspect, comprising the materials handling vehicle of thesixth aspect, the vehicle position processor is configured to navigatethe materials handling vehicle outside of the racking system aisle inthe modified operating state, in an additional operating state that iswithin or outside of the end-of-aisle limit, or in a combination ofoperating states selected therefrom.

In a tenth aspect, comprising the materials handling vehicle of any ofthe first aspect to the ninth aspect, the camera is further configuredto capture an image of an aisle entry identifier in a multilevelwarehouse racking system, and the vehicle position processor is furtherconfigured to generate end-of-aisle limit data comprising anend-of-aisle limit, end-of-aisle positional data, and aisle-specificrack leg spacing data from an image of an aisle entry identifier, ascaptured by the camera, generate an initial position of the materialshandling vehicle along the inventory transit surface using theend-of-aisle positional data, and generate an expected position of thematerials handling vehicle as the vehicle travels down a racking systemaisle corresponding to the aisle entry identifier from the end-of-aislepositional data, the aisle-specific rack leg spacing data, and thehorizontally advanced position. The vehicle position processor isfurther configured to determine whether the operating state of thematerials handling vehicle exceeds the end-of-aisle limit when theexpected position of the materials handling vehicle corresponds to anend of the racking system aisle, transmit a limit-based command to thedrive mechanism of the materials handling vehicle when the operatingstate of the materials handling vehicle exceeds the end-of-aisle limit,initiate a vehicle action based on the limit-based command, the vehicleaction configured to modify operation of the materials handling vehicleto a modified operating state within the end-of-aisle limit, andnavigate the materials handling vehicle to exit the racking system aislein the modified operating state.

In an eleventh aspect, comprising the materials handling vehicle of thetenth aspect, the vehicle position processor is further configured togenerate the expected position of the materials handling vehicle from animage of at least a portion of a rack leg positioned in the rackingsystem aisle.

In a twelfth aspect, comprising the materials handling vehicle of any ofthe first aspect to the eleventh aspect, the camera is configured tocapture images comprising an aisle entry identifier for a racking systemaisle of a multilevel warehouse racking system, and the vehicle positionprocessor is configured to generate end-of-aisle positional data andaisle-specific rack leg spacing data from an image of an aisle entryidentifier, as captured by the camera, generate an initial position ofthe materials handling vehicle along the inventory transit surface usingthe end-of-aisle positional data, and generate an expected position ofthe materials handling vehicle as the vehicle travels down a rackingsystem aisle corresponding to the aisle entry identifier from theend-of-aisle positional data, the aisle-specific rack leg spacing data,and the horizontally advanced position. The vehicle position processoris further configured to navigate the materials handling vehicle to exitthe racking system aisle, and update the expected position of thematerials handling vehicle using a dead reckoning component of thematerials handling vehicle when the materials handling vehicle isoutside of the racking system aisle.

In a thirteenth aspect, comprising the materials handling vehicle of anyof the first aspect to the twelfth aspect, the camera is configured tocapture images comprising an aisle exit identifier for a racking systemaisle of a multilevel warehouse racking system, and the vehicle positionprocessor is configured to generate end-of-aisle positional data from animage of an aisle exit identifier, as captured by the camera, generate avehicle pose of the materials handling vehicle relative to the aisleexit identifier using the end-of-aisle positional data, and generate aninventory transit surface position of the materials handling vehiclealong the inventory transit surface using the end-of-aisle positionaldata, the vehicle pose, and the horizontally advanced position. Thevehicle position processor is further configured to navigate thematerials handing vehicle to exit the racking system aisle, and updatethe inventory transit surface position of the materials handling vehicleusing a tag identifier component of the materials handling vehicle whenthe materials handling vehicle is outside of the racking system aisle.

In a fourteenth aspect, comprising the materials handling vehicle of thethirteenth aspect, the vehicle position processor is configured togenerate out-of-aisle positional data from a tag identifier, as receivedby the tag identifier component, and update the vehicle pose of thematerials handling vehicle relative to the tag identifier using theout-of-aisle positional data.

According to an embodiment, in a fifteenth aspect, a method oflocalizing a materials handling vehicle is recited, the vehiclecomprising a camera, a mast assembly, a mast assembly control unit, afork carriage assembly, a vehicle position processor, and a drivemechanism configured to move the materials handling vehicle along aninventory transit surface of a warehouse, wherein the mast assembly andthe mast assembly control unit are configured to move the fork carriageassembly along a vertical lift axis. The mast assembly and the mastassembly control unit are configured to move the fork carriage assemblyalong a vertical lift axis, and the camera is secured to the forkcarriage assembly and is configured to capture (i) a forks down image ofat least a portion of a rack leg positioned in a racking system aisle ofthe multilevel warehouse racking system, and (ii) a forks-up image of atleast a portion of a rack leg positioned in a racking system aisle ofthe multilevel warehouse racking system. The method comprises, via thevehicle position processor, generating a forks-down coordinate X1 of thecamera along a horizontal axis from the forks-down image of the rackleg, generating a forks-up coordinate X2 of the camera along ahorizontal axis from a forks-up image of the rack leg captured with thefork carriage assembly at a lift height H1, determining a mast swayoffset as a difference between the forks-down coordinate X1 and theforks-up coordinate X2, and determining a horizontally advanced positionof the materials handling vehicle with the fork carriage assembly at thelift height H1 using the mast sway offset and a subsequently capturedforks-up image of at least a portion of a rack leg positioned in theracking system aisle.

In a sixteenth aspect, comprising the method of the fifteenth aspect,the camera is further configured to capture an image of an aisle endidentifier in a multilevel warehouse racking system. The method furthercomprises generating end-of-aisle limit data comprising an end-of-aislelimit from an image of an aisle end identifier, as captured by thecamera, determining whether the materials handling vehicle exceeds theend-of-aisle limit, transmitting a limit-based command to the drivemechanism of the materials handling vehicle when an operating state ofthe materials handling vehicle exceeds the end-of-aisle limit,initiating a vehicle action based on the limit-based command, thevehicle action configured to modify operation of the materials handlingvehicle to a modified operating state within the end-of-aisle limit, andnavigating the materials handling vehicle to exit the racking systemaisle in the modified operating state.

In a seventeenth aspect, comprising the method of the fifteenth aspect,the camera is further configured to capture an image of an aisle entryidentifier in a multilevel warehouse racking system, and the methodfurther comprises generating end-of-aisle limit data comprising anend-of-aisle limit, end-of-aisle positional data, and aisle-specificrack leg spacing data from an image of an aisle entry identifier, ascaptured by the camera, generating an initial position of the materialshandling vehicle along the inventory transit surface using theend-of-aisle positional data, and generating an expected position of thematerials handling vehicle as the vehicle travels down a racking systemaisle corresponding to the aisle entry identifier from the end-of-aislepositional data, the aisle-specific rack leg spacing data, and thehorizontally advanced position. The method further comprises determiningwhether the operating state of the materials handling vehicle exceedsthe end-of-aisle limit when the expected position of the materialshandling vehicle corresponds to an end of the racking system aisle,transmitting a limit-based command to the drive mechanism of thematerials handling vehicle when the operating state of the materialshandling vehicle exceeds the end-of-aisle limit, initiating a vehicleaction based on the limit-based command, the vehicle action configuredto modify operation of the materials handling vehicle to a modifiedoperating state within the end-of-aisle limit, and navigating thematerials handling vehicle to exit the racking system aisle in themodified operating state.

In an eighteenth aspect, comprising any of the methods of the fifteenthaspect to the seventeenth aspect, the camera is configured to captureimages comprising an aisle entry identifier for a racking system aisleof a multilevel warehouse racking system, and the method furthercomprises generating end-of-aisle positional data and aisle-specificrack leg spacing data from an image of an aisle entry identifier, ascaptured by the camera, generating an initial position of the materialshandling vehicle along the inventory transit surface using theend-of-aisle positional data, generating an expected position of thematerials handling vehicle as the vehicle travels down a racking systemaisle corresponding to the aisle entry identifier from the end-of-aislepositional data, the aisle-specific rack leg spacing data, and thehorizontally advanced position, navigating the materials handlingvehicle to exit the racking system aisle, and updating the expectedposition of the materials handling vehicle using a dead reckoningcomponent of the materials handling vehicle when the materials handlingvehicle is outside of the racking system aisle.

In a nineteenth aspect, comprising the method of any of the fifteenthaspect to the eighteenth aspect, the camera is configured to captureimages comprising an aisle exit identifier for a racking system aisle ofa multilevel warehouse racking system, and the method further comprisesgenerating end-of-aisle positional data from an image of an aisle exitidentifier, as captured by the camera, generating a vehicle pose of thematerials handling vehicle relative to the aisle exit identifier usingthe end-of-aisle positional data, generating an inventory transitsurface position of the materials handling vehicle along the inventorytransit surface using the end-of-aisle positional data, the vehiclepose, and the horizontally advanced position, navigating the materialshanding vehicle to exit the racking system aisle, and updating theinventory transit surface position of the materials handling vehicleusing a tag identifier component of the materials handling vehicle whenthe materials handling vehicle is outside of the racking system aisle.

In a twentieth aspect, comprising the method of the nineteenth aspect,the method further comprises generating out-of-aisle positional datafrom a tag identifier, as received by the tag identifier component, andupdating the vehicle pose of the materials handling vehicle relative tothe tag identifier using the out-of-aisle positional data.

In another embodiment, according to a twenty-first aspect, a materialshandling vehicle comprises a camera, a vehicle position processor, and adrive mechanism configured to move the materials handling vehicle alongan inventory transit surface. The camera is configured to capture animage comprising an aisle end identifier for a racking system aisle of amultilevel warehouse racking system, and the vehicle position processoris configured to generate end-of-aisle limit data comprising anend-of-aisle limit from an image of an aisle end identifier, as capturedby the camera, determine whether the materials handling vehicle exceedsthe end-of-aisle limit, transmit a limit-based command to the drivemechanism of the materials handling vehicle when an operating state ofthe materials handling vehicle exceeds the end-of-aisle limit, initiatea vehicle action based on the limit-based command, the vehicle actionconfigured to modify operation of the materials handling vehicle to amodified operating state within the end-of-aisle limit, and navigate thematerials handling vehicle to exit the racking system aisle in themodified operating state.

In a twenty-second aspect, comprising the materials handling vehicle ofthe twenty-first aspect, the end-of-aisle limit comprises a speed limit,a lift height limit, an acceleration limit, a deceleration limit, a liftacceleration limit, a lift deceleration limit, or combinations thereof.

In a twenty-third aspect, comprising the materials handling vehicle ofthe twenty-first aspect or the twenty-second aspect, the vehicleposition processor is configured to navigate the materials handlingvehicle outside of the racking system aisle in the modified operatingstate, in an additional operating state that is within or outside of theend-of-aisle limit, or in a combination of operating states selectedtherefrom.

In a twenty-fourth aspect, comprising the materials handling vehicle ofany of the twenty-first aspect to the twenty-third aspect, the aisle endidentifier is disposed on an aisle end rack leg.

In a twenty-fifth aspect, comprising the materials handling vehicle ofany of the twenty-first aspect to the twenty-fourth aspect, the aisleend identifier is disposed on an end rack leg of the racking systemaisle.

In a twenty-sixth aspect, comprising the materials handling vehicle ofany of the twenty-first aspect to the twenty-fifth aspect, the camera isconfigured to capture images comprising an aisle entry identifier for aracking system aisle of a multilevel warehouse racking system, and thevehicle position processor is configured to generate end-of-aislepositional data and aisle-specific rack leg spacing data from an imageof an aisle entry identifier, as captured by the camera, generate aninitial position of the materials handling vehicle along the inventorytransit surface using the end-of-aisle positional data, generate anexpected position of the materials handling vehicle as the vehicletravels down the racking system aisle corresponding to the aisle entryidentifier from the end-of-aisle positional data and the aisle-specificrack leg spacing data, and determine whether the operating state of thematerials handling vehicle exceeds the end-of-aisle limit when theexpected position of the materials handling vehicle corresponds to anend of the racking system aisle.

In a twenty-seventh aspect, comprising the materials handling vehicle ofthe twenty-sixth aspect, the vehicle position processor is furtherconfigured to generate the expected position of the materials handlingvehicle from an image of at least a portion of a rack leg positioned inthe racking system aisle.

In a twenty-eighth aspect, comprising the materials handling vehicle ofany of the twenty-first aspect to the twenty-seventh aspect, thematerials handling vehicle further comprises a mast assembly, a mastassembly control unit, and a fork carriage assembly, the mast assemblyand the mast assembly control unit are configured to move the forkcarriage assembly along a vertical lift axis, and the camera is securedto the fork carriage assembly and is configured to capture (i) a forksdown image of at least a portion of a rack leg positioned in a rackingsystem aisle of the multilevel warehouse racking system, and (ii) aforks-up image of at least a portion of a rack leg positioned in aracking system aisle of the multilevel warehouse racking system. Thevehicle position processor is configured to generate a forks-downcoordinate X1 of the camera along a horizontal axis from the forks-downimage of the rack leg, generate a forks-up coordinate X2 of the cameraalong a horizontal axis from a forks-up image of the rack leg capturedwith the fork carriage assembly at a lift height H1, determine a mastsway offset as a difference between the forks-down coordinate X1 and theforks-up coordinate X2, and determine a horizontally advanced positionof the materials handling vehicle with the fork carriage assembly at thelift height H1 using the mast sway offset and a subsequently capturedforks-up image of at least a portion of a rack leg positioned in theracking system aisle.

In a twenty-ninth aspect, comprising the materials handling vehicle ofany of the twenty-first aspect to the twenty-eighth aspect, the camerais configured to capture images comprising an aisle entry identifier fora racking system aisle of a multilevel warehouse racking system, and thevehicle position processor is configured to generate end-of-aislepositional data and aisle-specific rack leg spacing data from an imageof an aisle entry identifier, as captured by the camera, generate aninitial position of the materials handling vehicle along the inventorytransit surface using the end-of-aisle positional data, and generate anexpected position of the materials handling vehicle as the vehicletravels down a racking system aisle corresponding to the aisle entryidentifier from the end-of-aisle positional data and the aisle-specificrack leg spacing data. The vehicle position processor is furtherconfigured to navigate the materials handling vehicle to exit theracking system aisle, and update the expected position of the materialshandling vehicle using a dead reckoning component of the materialshandling vehicle when the materials handling vehicle is outside of theracking system aisle.

In a thirtieth aspect, comprising the materials handling vehicle of anyof the twenty-first aspect to the twenty-ninth aspect, the camera isconfigured to capture images comprising an aisle exit identifier for aracking system aisle of a multilevel warehouse racking system, and thethe vehicle position processor is configured to generate end-of-aislepositional data from an image of an aisle exit identifier, as capturedby the camera, generate a vehicle pose of the materials handling vehiclerelative to the aisle exit identifier using the end-of-aisle positionaldata, generate an inventory transit surface position of the materialshandling vehicle along the inventory transit surface using theend-of-aisle positional data and the vehicle pose, and navigate thematerials handing vehicle to exit the racking system aisle, and updatethe inventory transit surface position of the materials handling vehicleusing a tag identifier component of the materials handling vehicle whenthe materials handling vehicle is outside of the racking system aisle.

In a thirty-first aspect, comprising the materials handling vehicle ofthe thirtieth aspect, the vehicle position processor is configured togenerate out-of-aisle positional data from a tag identifier, as receivedby the tag identifier component, and update the vehicle pose of thematerials handling vehicle relative to the tag identifier using theout-of-aisle positional data.

According to another embodiment, in a thirty-second aspect, a materialshandling vehicle comprising a camera, a vehicle position processor, anda drive mechanism configured to move the materials handling vehiclealong an inventory transit surface, wherein the camera is configured tocapture an image comprising an aisle entry identifier for a rackingsystem aisle of a multilevel warehouse racking system. The vehicleposition processor is configured to generate end-of-aisle limit datacomprising an end-of-aisle limit, end-of-aisle positional data, andaisle-specific rack leg spacing data from an image of an aisle entryidentifier, as captured by the camera, generate an initial position ofthe materials handling vehicle along the inventory transit surface usingthe end-of-aisle positional data, and generate an expected position ofthe materials handling vehicle as the vehicle travels down a rackingsystem aisle corresponding to the aisle entry identifier from theend-of-aisle positional data and the aisle-specific rack leg spacingdata. The vehicle position processor is further configured to determinewhether the operating state of the materials handling vehicle exceedsthe end-of-aisle limit when the expected position of the materialshandling vehicle corresponds to an end of the racking system aisle,transmit a limit-based command to the drive mechanism of the materialshandling vehicle when the operating state of the materials handlingvehicle exceeds the end-of-aisle limit, initiate a vehicle action basedon the limit-based command, the vehicle action configured to modifyoperation of the materials handling vehicle to a modified operatingstate within the end-of-aisle limit, and navigate the materials handlingvehicle to exit the racking system aisle in the modified operatingstate.

In a thirty-third aspect, comprising the materials handling vehicle ofthe thirty-second aspect, the vehicle position processor is furtherconfigured to generate the expected position of the materials handlingvehicle from an image of at least a portion of a rack leg positioned inthe racking system aisle.

In a thirty-fourth aspect, comprising the materials handling vehicle ofthe thirty-second aspect or the thirty-third aspect, the aisle entryidentifier is disposed on an end rack leg of the racking system aisle.

In a thirty-fifth aspect, comprising the materials handling vehicle ofany of the thirty-second aspect to the thirty-fourth aspect, thematerials handling vehicle further comprises a mast assembly, a mastassembly control unit, and a fork carriage assembly, the mast assemblyand the mast assembly control unit are configured to move the forkcarriage assembly along a vertical lift axis, and the camera is securedto the fork carriage assembly and is configured to capture (i) a forksdown image of at least a portion of a rack leg positioned in the rackingsystem aisle of the multilevel warehouse racking system, and (ii) aforks-up image of at least a portion of a rack leg positioned in theracking system aisle of the multilevel warehouse racking system. Thevehicle position processor is configured to generate a forks-downcoordinate X1 of the camera along a horizontal axis from the forks-downimage of the rack leg, generate a forks-up coordinate X2 of the cameraalong a horizontal axis from a forks-up image of the rack leg capturedwith the fork carriage assembly at a lift height H1, determine a mastsway offset as a difference between the forks-down coordinate X1 and theforks-up coordinate X2, determine a horizontally advanced position ofthe materials handling vehicle with the fork carriage assembly at thelift height H1 using aisle-specific rack leg spacing data in addition tothe mast sway offset and a subsequently captured forks-up image of atleast a portion of a rack leg positioned in the racking system aisle,and update the expected position using the horizontally advancedposition.

In a thirty-sixth aspect, comprising the materials handling vehicle ofany of the thirty-second aspect to the thirty-fifth aspect, the vehicleposition processor is configured to update the expected position of thematerials handling vehicle using a dead reckoning component of thematerials handling vehicle when the materials handling vehicle isoutside of the racking system aisle.

In a thirty-seventh aspect, comprising the materials handling vehicle ofany of the thirty-second aspect to the thirty-sixth aspect, the camerais configured to capture images comprising an aisle exit identifier fora racking system aisle of a multilevel warehouse racking system, and thevehicle position processor is configured to generate end-of-aislepositional data from an image of an aisle exit identifier, as capturedby the camera, generate a vehicle pose of the materials handling vehiclerelative to the aisle exit identifier using the end-of-aisle positionaldata, generate an inventory transit surface position of the materialshandling vehicle along the inventory transit surface using theend-of-aisle positional data, the vehicle pose, and the expectedposition, navigate the materials handing vehicle to exit the rackingsystem aisle, and update the inventory transit surface position of thematerials handling vehicle using a tag identifier component of thematerials handling vehicle when the materials handling vehicle isoutside of the racking system aisle.

In a thirty-eighth aspect, comprising the materials handling vehicle ofthe thirty-seventh aspect, the vehicle position processor is configuredto generate out-of-aisle positional data from a tag identifier, asreceived by the tag identifier component, and update the vehicle pose ofthe materials handling vehicle relative to the tag identifier using theout-of-aisle positional data.

In yet another embodiment, in a thirty-ninth aspect, a materialshandling vehicle comprises a camera, a vehicle position processor, and adrive mechanism configured to move the materials handling vehicle alongan inventory transit surface, and the camera is configured to captureimages comprising (i) an aisle entry identifier for a racking systemaisle of a multilevel warehouse racking system, and (ii) at least aportion of a rack leg positioned in the racking system aisle. Thevehicle position processor is configured to generate end-of-aislepositional data and aisle-specific rack leg spacing data from an imageof an aisle entry identifier, as captured by the camera, generate aninitial position of the materials handling vehicle along the inventorytransit surface using the end-of-aisle positional data, generate anexpected position of the materials handling vehicle as the vehicletravels down a racking system aisle corresponding to the aisle entryidentifier from the end-of-aisle positional data and the aisle-specificrack leg spacing data, navigate the materials handling vehicle to exitthe racking system aisle, and update the expected position of thematerials handling vehicle using a dead reckoning component of thematerials handling vehicle when the materials handling vehicle isoutside of the racking system aisle.

In a fortieth aspect, comprising the materials handling vehicle of thethirty-ninth aspect, the camera is configured to capture imagescomprising an aisle exit identifier for a racking system aisle of amultilevel warehouse racking system, and the vehicle position processoris configured to generate end-of-aisle positional data from an image ofan aisle exit identifier, as captured by the camera, generate a vehiclepose of the materials handling vehicle relative to the aisle exitidentifier using the end-of-aisle positional data, generate an inventorytransit surface position of the materials handling vehicle along theinventory transit surface using the end-of-aisle positional data, thevehicle pose, and the expected position, navigate the materials handingvehicle to exit the racking system aisle, and update the inventorytransit surface position of the materials handling vehicle using a tagidentifier component of the materials handling vehicle when thematerials handling vehicle is outside of the racking system aisle.

In a forty-first aspect, comprising the materials handling vehicle ofthe fortieth aspect, the vehicle position processor is configured togenerate out-of-aisle positional data from a tag identifier, as receivedby the tag identifier component, and update the vehicle pose of thematerials handling vehicle relative to the tag identifier using theout-of-aisle positional data.

In a forty-second aspect, comprising the materials handling vehicle ofany of the thirty-ninth aspect to the forty-first aspect, the materialshandling vehicle further comprises a mast assembly, a mast assemblycontrol unit, and a fork carriage assembly, the mast assembly and themast assembly control unit are configured to move the fork carriageassembly along a vertical lift axis, and the camera is secured to thefork carriage assembly and is configured to capture (i) a forks downimage of at least a portion of a rack leg positioned in a racking systemaisle of the multilevel warehouse racking system, and (ii) a forks-upimage of at least a portion of a rack leg positioned in a racking systemaisle of the multilevel warehouse racking system. The vehicle positionprocessor is configured to generate a forks-down coordinate X1 of thecamera along a horizontal axis from the forks-down image of the rackleg, generate a forks-up coordinate X2 of the camera along a horizontalaxis from a forks-up image of the rack leg captured with the forkcarriage assembly at a lift height H1, and determine a mast sway offsetas a difference between the forks-down coordinate X1 and the forks-upcoordinate X2. The vehicle position processor is further configured todetermine a horizontally advanced position of the materials handlingvehicle with the fork carriage assembly at the lift height H1 using themast sway offset and a subsequently captured forks-up image of at leasta portion of a rack leg positioned in the racking system aisle, andupdate the expected position using the horizontally advanced position.

In a forty-third aspect, comprising the materials handling vehicle ofany of the thirty-ninth aspect to the forty-second aspect, the vehicleposition processor is configured to generate end-of-aisle limit datacomprising an end-of-aisle limit from the image of the aisle entryidentifier, as captured by the camera, determine whether the materialshandling vehicle exceeds the end-of-aisle limit, and transmit alimit-based command to the drive mechanism of the materials handlingvehicle when an operating state of the materials handling vehicleexceeds the end-of-aisle limit. The vehicle position processor isfurther configured to initiate a vehicle action based on the limit-basedcommand, the vehicle action configured to modify operation of thematerials handling vehicle to a modified operating state within theend-of-aisle limit, and navigate the materials handling vehicle to exitthe racking system aisle in the modified operating state.

In a forty-fourth aspect, comprising the materials handling vehicle ofthe forty-third aspect, the end-of-aisle limit comprises a speed limit,a lift height limit, an acceleration limit, a deceleration limit, a liftacceleration limit, a lift deceleration limit, or combinations thereof.

In a forty-fifth aspect, comprising the materials handling vehicle ofthe forty-third aspect or the forty-fourth aspect, the vehicle positionprocessor is configured to navigate the materials handling vehicleoutside of the racking system aisle in the modified operating state, inan additional operating state that is within or outside of theend-of-aisle limit, or in a combination of operating states selectedtherefrom.

In a forty-sixth aspect, comprising the materials handling vehicle ofany of the forty-third aspect to the forty-fifth aspect, the vehicleposition processor is configured to determine whether the operatingstate of the materials handling vehicle exceeds the end-of-aisle limitwhen the expected position of the materials handling vehicle correspondsto an end of the racking system aisle.

In one other embodiment, in a forty-seventh aspect, a materials handlingvehicle comprising a camera, a vehicle position processor, and a drivemechanism configured to move the materials handling vehicle along aninventory transit surface, wherein the camera is configured to captureimages comprising an aisle exit identifier for a racking system aisle ofa multilevel warehouse racking system. The vehicle position processor isconfigured to generate end-of-aisle positional data from an image of anaisle exit identifier, as captured by the camera, generate a vehiclepose of the materials handling vehicle relative to the aisle exitidentifier using the end-of-aisle positional data, generate an inventorytransit surface position of the materials handling vehicle along theinventory transit surface using the end-of-aisle positional data and thevehicle pose, navigate the materials handing vehicle to exit the rackingsystem aisle, and update the inventory transit surface position of thematerials handling vehicle using a tag identifier component of thematerials handling vehicle when the materials handling vehicle isoutside of the racking system aisle.

In a forty-eighth aspect, comprising the materials handling vehicle ofthe forty-seventh aspect, the vehicle position processor is configuredto generate out-of-aisle positional data from a tag identifier, asreceived by the tag identifier component, and update the vehicle pose ofthe materials handling vehicle relative to the tag identifier using theout-of-aisle positional data.

In a forty-ninth aspect, comprising the materials handling vehicle ofthe forty-seventh aspect or the forty-eighth aspect, the vehicleposition processor is further configured to generate the inventorytransit surface position of the materials handling vehicle from an imageof at least a portion of a rack leg positioned in the racking systemaisle.

In a fiftieth aspect, comprising the materials handling vehicle of anyof the forty-seventh aspect to the forty-ninth aspect, the camera isconfigured to capture images comprising (i) an aisle entry identifierfor a racking system aisle of the multilevel warehouse racking system,and (ii) at least a portion of a rack leg positioned in the rackingsystem aisle. The vehicle position processor is configured to generateend-of-aisle positional data and aisle-specific rack leg spacing datafrom an image of an aisle entry identifier, as captured by the camera,generate an initial position of the materials handling vehicle along theinventory transit surface in a racking system aisle using theend-of-aisle positional data, generate an expected position of thematerials handling vehicle as the vehicle travels down the rackingsystem aisle corresponding to the aisle entry identifier from theend-of-aisle positional data and the aisle-specific rack leg spacingdata, and update the inventory transit surface position using theexpected position.

In a fifty-first aspect, comprising the materials handling vehicle ofthe fiftieth aspect, the vehicle position processor is furtherconfigured to update the inventory transit surface position of thematerials handling vehicle using a dead reckoning component of thematerials handling vehicle when the materials handling vehicle isoutside of the racking system aisle.

In a fifty-second aspect, comprising the materials handling vehicle ofany of the forty-seventh aspect to the fifty-first aspect, the materialshandling vehicle further comprises a mast assembly, a mast assemblycontrol unit, and a fork carriage assembly, the mast assembly and themast assembly control unit are configured to move the fork carriageassembly along a vertical lift axis, and the camera is secured to thefork carriage assembly and is configured to capture (i) a forks-downimage of at least a portion of a rack leg positioned in a racking systemaisle of the multilevel warehouse racking system, and a forks-up imageof at least a portion of a rack leg positioned in a racking system aisleof the multilevel warehouse racking system. The vehicle positionprocessor is configured to generate a forks-down coordinate X1 of thecamera along a horizontal axis from the forks-down image of the rackleg, generate a forks-up coordinate X2 of the camera along a horizontalaxis from a forks-up image of the rack leg captured with the forkcarriage assembly at a lift height H1, determine a mast sway offset as adifference between the forks-down coordinate X1 and the forks-upcoordinate X2, determine a horizontally advanced position of thematerials handling vehicle with the fork carriage assembly at the liftheight H1 using the mast sway offset and a subsequently capturedforks-up image of at least a portion of a rack leg positioned in theracking system aisle, and update the inventory transit surface positionusing the horizontally advanced position.

In a fifty-third aspect, comprising the materials handling vehicle ofany of the forty-seventh aspect to the fifty-second aspect, the vehicleposition processor is configured to generate end-of-aisle limit datacomprising an end-of-aisle limit from the image of the aisle exitidentifier, as captured by the camera, determine whether the materialshandling vehicle exceeds the end-of-aisle limit, transmit a limit-basedcommand to the drive mechanism of the materials handling vehicle when anoperating state of the materials handling vehicle exceeds theend-of-aisle limit, initiate a vehicle action based on the limit-basedcommand, the vehicle action configured to modify operation of thematerials handling vehicle to a modified operating state within theend-of-aisle limit, and navigate the materials handling vehicle to exitthe racking system aisle in the modified operating state.

In a fifty-fourth aspect, comprising the materials handling vehicle ofthe fifty-third aspect, the end-of-aisle limit comprises a speed limit,a lift height limit, an acceleration limit, a deceleration limit, a liftacceleration limit, a lift deceleration limit, or combinations thereof.

In a fifty-fifth aspect, comprising the materials handling vehicle ofthe fifty-third aspect or the fifty-fourth aspect, the vehicle positionprocessor is configured to navigate the materials handling vehicleoutside of the racking system aisle in the modified operating state, inan additional operating state that is within or outside of theend-of-aisle limit, or in a combination of operating states selectedtherefrom.

In a fifty-sixth aspect, comprising the materials handling vehicle ofany of the forty-seventh aspect to the fifty-fifth aspect, the camera isconfigured to capture an image comprising an aisle entry identifier fora racking system aisle of a multilevel warehouse racking system, and thevehicle position processor is configured to generate end-of-aisle limitdata comprising an end-of-aisle limit from the image of the aisle entryidentifier, as captured by the camera, determine whether an operatingstate of the materials handling vehicle exceeds the end-of-aisle limitwhen the inventory transit surface position of the materials handlingvehicle corresponds to an end of the racking system aisle, transmit alimit-based command to the drive mechanism of the materials handlingvehicle when the operating state of the materials handling vehicleexceeds the end-of-aisle limit, initiate a vehicle action based on thelimit-based command, the vehicle action configured to modify operationof the materials handling vehicle to a modified operating state withinthe end-of-aisle limit, and navigate the materials handling vehicle toexit the racking system aisle in the modified operating state.

These and additional features provided by the embodiments describedherein will be more fully understood in view of the following detaileddescription, in conjunction with the drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The embodiments set forth in the drawings are illustrative and exemplaryin nature and not intended to limit the subject matter defined by theclaims. The following detailed description of the illustrativeembodiments can be understood when read in conjunction with thefollowing drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1A depicts a plurality of vehicles for localization in a warehouseincluding a warehouse racking system, according to one or moreembodiments shown and described herein;

FIG. 1B depicts a schematic plan view of a warehouse environmentutilizing tag reading technology and out of aisle identifier technology,according to one or more embodiments shown and described herein

FIG. 2 depicts a rack leg imaging module on a vehicle of the pluralityof vehicles of FIG. 1A, according to one or more embodiments shown anddescribed herein;

FIG. 3 depicts an image of a rack leg feature of the warehouse rackingsystem of FIG. 1A as captured by the rack leg imaging module of FIG. 2 ,according to one or more embodiments shown and described herein;

FIG. 4 depicts a schematic illustration of a system including a rack legimaging module system and for implementing computer and software basedmethods to utilize the rack leg imaging module of FIG. 2 , according toone or more embodiments shown and described herein;

FIG. 5 depicts a schematic illustration of the rack leg imaging modulesystem of FIG. 4 including a rack leg imaging module, a control module,and a vehicle controller;

FIG. 6 depicts a flowchart overview of a method for a localizationmethod according to one or more embodiments shown and described herein;

FIG. 7 depicts a schematic illustration of a materials handling vehicleincluding a raisable fork carriage assembly with the rack leg imagingmodule of FIG. 2 and illustrating a mast sway offset between forkcarriage assembly positions, according to one or more embodiments shownand described herein;

FIG. 8A depicts a schematic illustration of the materials handlingvehicle in FIG. 7 in a first embodiment including the rack leg imagingmodule on the raisable fork carriage assembly on a first side of thematerials handling vehicle and a lower, fixed rack leg imaging module ona second side opposite the first side of the materials handling vehicle;

FIG. 8B depicts a schematic illustration of the materials handlingvehicle in FIG. 7 in a second embodiment including the rack leg imagingmodule on the raisable fork carriage assembly on the second side of thematerials handling vehicle and the lower, fixed rack leg imaging moduleon the first side of the materials handling vehicle;

FIG. 8C depicts a schematic illustration of the materials handlingvehicle in FIG. 7 in a third embodiment including the rack leg imagingmodule on the raisable fork carriage assembly on the first side of thematerials handling vehicle and the lower, fixed rack leg imaging moduleon the first side of the materials handling vehicle;

FIG. 8D depicts a schematic illustration of the materials handlingvehicle in FIG. 7 in a fourth embodiment including the rack leg imagingmodule on the raisable fork carriage assembly on the second side of thematerials handling vehicle and the lower, fixed rack leg imaging moduleon the second side of the materials handling vehicle;

FIG. 8E depicts a schematic illustration of the materials handlingvehicle in FIG. 7 in a fifth embodiment including the rack leg imagingmodule on the raisable fork carriage assembly on the first side of thematerials handling vehicle and another rack leg imaging module on theraisable fork carriage assembly on the second side of the materialshandling vehicle;

FIG. 8F depicts a schematic illustration of a materials handling vehiclein an embodiment including a fixed rack leg imaging module on a powerunit assembly on the first side of the materials handling vehicle andanother fixed rack leg imaging module on the power unit assembly on thesecond side of the materials handling vehicle, according to one or moreembodiments shown and described herein;

FIG. 9 depicts a schematic illustration of another embodiment of therack leg imaging module system of FIG. 4 including a pair of rack legimaging modules and a control module;

FIG. 10 depicts a schematic illustration of yet another embodiment ofthe rack leg imaging module system of FIG. 4 including a position ofrack leg imaging modules and a pair of control modules; and

FIG. 11 depicts a flowchart overview of a method for a mast sway offsetcompensation, according to one or more embodiments shown and describedherein.

FIG. 12 depicts a flowchart overview of a vehicle end of aisle limitdetermination method, according to one or more embodiments shown anddescribed herein; and

FIG. 13 depicts a flowchart overview of a vehicle end of aisle limitdetermination method based on data redundancy, according to one or moreembodiments shown and described herein;

FIG. 14 depicts a flowchart overview of a method for an out of aisledead reckoning localization continuation method, according to one ormore embodiments shown and described herein; and

FIG. 15 depicts a flowchart overview of a method for an out of aisleidentifier localization continuation method, according to one or moreembodiments shown and described herein.

DETAILED DESCRIPTION

The embodiments described herein generally relate to localizationtechniques for extracting features from rack leg features through use ofone or more rack leg imaging modules as described herein. Localizationis utilized herein to refer to any of a variety of system configurationsthat enable active tracking of a vehicle location in a warehouse,industrial or commercial facility, or other environment. For thepurposes of defining and describing the concepts and scope of thepresent disclosure, it is noted that a “warehouse” encompasses anyindoor or outdoor industrial facility in which materials handlingvehicles transport goods including, but not limited to, indoor oroutdoor industrial facilities that are intended primarily for thestorage of goods, such as those where multi-level racks are arranged inaisles, and manufacturing facilities where goods are transported aboutthe facility by materials handling vehicles for use in one or moremanufacturing processes. The concepts of the present disclosure are notlimited to any particular localization system configuration and aredeemed to be applicable to any of a variety of conventional andyet-to-be developed localization systems. Such localizations systems mayinclude those described in U.S. Pat. No. 9,349,181 issued on May 24,2016, entitled LOST VEHICLE RECOVERY UTILIZING ASSOCIATED FEATURE PAIRS,and U.S. Pat. No. 9,984,467 issued May 29, 2018, entitled VEHICLEPOSITIONING OR NAVIGATION UTILIZING ASSOCIATED FEATURE PAIRS.

The localization systems may be used to localize and/or navigate anindustrial vehicle through a warehouse environment 150 (FIG. 1B) thatincludes a racking structure, which may be a warehouse, stock yard, orthe like. Suitably, the rack leg features may be utilized by a rack legimaging module to capture images of the rack leg features to initializelocalization and update accumulated odometry as described herein. Insome embodiments, the rack leg imaging module including a camera can bemounted to an industrial vehicle (e.g., automated guided vehicle or amanually guided vehicle) that navigates through a warehouse. The inputimage can be any image captured from the camera prior to extractingfeatures from the image.

Referring now to FIG. 1A, a materials handling vehicle 102 can beconfigured to navigate through a warehouse environment 150 (FIG. 1B)such as a warehouse 11. The materials handling vehicle 102 can comprisea drive mechanism configured to move the materials handling vehicle 102along an inventory transit surface 106, a materials handling mechanismconfigured to place goods on and/or retrieve goods from a storage bay ofa multilevel warehouse racking system 12 in the warehouse 11 of thewarehouse environment 150, and vehicle control architecture incommunication with the drive and materials handling mechanisms. In anembodiment, the materials handling mechanism is configured to movematerials along a vertically-oriented materials handling axis.

The materials handling vehicle 102 can comprise an industrial vehiclefor lifting and moving a payload such as, for example, a forklift truck,a reach truck, a turret truck, a walkie stacker truck, a tow tractor, apallet truck, a high/low, a stacker-truck, trailer loader, a sideloader,a fork hoist, or the like. The aforementioned materials handlingvehicles such as the vehicle 102 may include lift trucks available fromCrown Equipment Corporation such as, for example, SP Series OrderPickers such as the Crown SP 3500/4500 Series Order Picker and/or TSPTurret Trucks such as one of the TSP 6500 Truck Series. The materialshandling vehicles may incorporate automated guidance vehicle (“AGV”)functionality using, for example, wire guidance or other guidancefeatures for AGV positioning system functionality.

The industrial vehicle can be configured to automatically or manuallynavigate an inventory transit surface 106 of the warehouse 11 along adesired path. Accordingly, the materials handling vehicle 102 can bedirected forwards and backwards by rotation of one or more wheels 210.Additionally, the materials handling vehicle 102 can be caused to changedirection by steering the one or more wheels 210. Optionally, thevehicle can comprise operator controls for controlling functions of thevehicle such as, but not limited to, the speed of the wheels 210, theorientation of the wheels 210, or the like. The operator controls cancomprise controls that are assigned to the functions of the materialshandling vehicle 102 such as, for example, switches, buttons, levers,handles, pedals, input/output device, or the like. It is noted that theterm “navigate” as used herein means movement control or route planningof a vehicle from one place to another including, but not limited to,plotting a graphical path for a manual vehicle operation, providing aset of turn by turn instructions for manual operation, or providing anautomated control guiding the vehicle along a travel path that mayinclude such turn by turn instructions for automated operation.

The warehouse 11 may include the warehouse racking system 12 having aplurality of racks 400 including a plurality of shelves defined betweena set of upright rails 406 of a rack 400. Each upright rail 406 of therack 400 has a rack leg 408 configured to be disposed on and support theupright rail 406 with respect to the inventory transit surface 106. Aracking system aisle 70′ for navigation of the materials handlingvehicle 102 on the inventory transit surface 106 may be defined betweena pair of opposing upright rails 406 of racks 400. Alternatively, theracking system aisle 70′ or portions of the racking system aisle 70′ maybe defined by at least one rack 400 and an opposite defining componentsuch as, but not limited to, one or more pallet stacks, a mezzanine, avirtually defined aisle boundary, or the like. Each end of the pair ofopposing upright rails 406 is configured to act as an entrance end or anexit end for the materials handling vehicle 102 into the racking systemaisle 70′. Identifiers 302, which may be aisle entry identifiers, aisleend identifiers, and/or aisle exit identifiers, may be disposed on therack legs 408 of at least the exit and entrance ends of the pair ofopposing upright rails 406 that form a racking system aisle 70′. Theidentifiers 302 may include, but are not limited to, stickers or otheradhesive or attachable components that include unique codes such asQuick Response (QR) codes. The QR codes may store and provideinformation about a rack leg 408 including, but not limited to, aposition of the rack leg 408 within the warehouse 11 as stored in awarehouse map 30, described in greater detail below. It is to beunderstood that information described as stored in any type of theidentifiers 302 described herein may be stored in other types ofidentifiers as described herein as well. For example, information storedin a described aisle entry identifier 302 as described herein may alsobe stored in an aisle end identifier 302 or an aisle exit identifier302, information stored in a described aisle end identifier 302 asdescribed herein may also be stored in an aisle entry identifier 302 oran aisle exit identifier 302, and information stored in a describedaisle exit identifier 302 as described herein may also be stored in anaisle entry identifier 302 or an aisle end identifier 302.

The aisle entry identifier 302 may include a QR code configured to storeand provide the racking system information, which may includeinformation about a hole pattern associated with a set of rack legs 408of the racking system aisle 70′ of the multilevel warehouse rackingsystem 12, the set of rack legs 408 including the initial rack leg 408,information about distances between adjacent rack legs 408 of the set ofrack legs 408, distance of a rack face of the racking system aisle 70′of the multilevel warehouse racking system 12 to a guidance wire in theracking system aisle 70′, a number of rack legs 408 of the set of racklegs 408 of the racking system aisle 70′ of the multilevel warehouseracking system 12, or combinations thereof. In embodiments, theinformation about the hole pattern may include distances between rows ofholes and distances between columns of holes of each rack leg 408 of theracking system aisle 70′ of the multilevel warehouse racking system 12.The racking system information may further include information regardinga distance between rack legs 408 in the racking system aisle 70′, andthe expected position is calculated by adding the distance between racklegs 408 in the racking system aisle 70′ to a previous distanceassociated with a previously detected rack leg 408.

Thus, the QR codes may further store and provide information including,but not limited to, information about a hole pattern associated with aset of rack legs 408 of a rack 400 defining an outer aisle boundary,distances between rack legs 408 of the rack 400 referable to herein as a“tick” distance, the rack 400 defining the outer aisle boundary,distance from a rack face of the rack 400 to a guidance wire for a givenracking system aisle 70′, and decoding data configured to permitdecoding of a localization target string into a target pose. The holepattern information may include, for example, distances between rows anddistances between columns of holes of a rack leg 408. The QR codes mayfurther store and provide information about a number of rack legs 408 ina given racking system aisle 70′ based on information associated with anobserved rack leg 408. Thus, the QR codes may contain data about a rackleg pattern, rack leg spacing, number of rack legs, and rack distancefrom a materials handling vehicle 102 centerline along with a guidancewire on the inventory transit surface 106 in a racking system aisle 70′for a plurality of rack legs 408 associated with the racking systemaisle 70′ to allow for subsequent use of the plurality of rack legs 408associated with the racking system aisle 70′ for localization of thematerials handling vehicle 102. The materials handling vehicle 102 maybe configured to be disposed on a guidance system, such as the guidancewire that may be utilized as a wire guidance for vehicle navigation onthe inventory transit surface 106, a guidance rail utilized for vehiclenavigation on the inventory transit surface 106, or the like. It iscontemplated within the scope of this disclosure that the embodimentsdescribed herein may be utilized with such types of guidance systems asdescribed or yet-to-be-developed. In embodiments, different rackingsystem aisles 70′ in the warehouse may have different spacing betweenupright rails 406 of a rack 400 and different types of racking of racks400 in the racking system 12.

Referring to FIG. 1B, the warehouse environment 150, which may be thewarehouse 11 (FIG. 1A), may include the aisle entry identifiers 302 on arack 400, one or more out of aisle tag identifiers 71, and/or tagreading technology associated with path defining components 410 such aspallets and/or racks 400. Similar to the rack leg identifiers 302, theone or more out of aisle identifiers 71 may include, but are not limitedto, stickers or other adhesive or attachable components that includeunique codes such as Quick Response (QR) codes. The tag readingtechnology may include, for example, a tag layout 50 in a single aislepath 70 (FIG. 2 ) of a racking system aisle 70′ (FIG. 1A), an example ofwhich is described in U.S. Pat. No. 9,811,088 assigned to CrownEquipment Corporation. The tag layout 50 can be constructed to compriseindividual tags, such as radio frequency identification (RFID) tags,that are positioned such that the materials handling vehicle 102 willoperate under a defined set of vehicle functionality (e.g., vehiclefunction data) and/or tag-dependent position data that will endure untilthe materials handling vehicle 102 identifies another individual tag ofthe tag layout 50 with a new correlation of vehicle functionality.Information about a first rack leg 408 may be stored in, or accessiblefrom, a table using an individual tag associated with the first rack leg408 such as an RFID tag disposed in a floor surface at the beginning ofa racking system aisle 70′, where the first rack leg 408 may be placedat the beginning of the racking system aisle 70′ or further down theracking system aisle 70′. As a non-limiting example, a set of palletsmay be placed in an aisle prior to a rack 400 including the first rackleg 408, and the RFID tag may be placed at the beginning of the aisle tocontain information about the first rack leg 408 and the rack 400.

In operation, by way of example and not as a limitation, the tag layout50 may be utilized with respect to a tag reader 33 and the reader module35 of the materials handling vehicle 102 (FIG. 2 ), examples of whichare also described in U.S. Pat. No. 9,811,088 assigned to CrownEquipment Corporation. The reader module 35 may include a reader memorycoupled to a reader processor. The tag reader 33 and the reader module35 may cooperate to identify individual tags of a tag layout 50. Eachindividual tag of the tag layout 50 may correspond to a uniqueidentification code, such as a code including rack leg information of arack leg 408 associated with an individual tag at the beginning of theaisle path 70 of the racking system aisle 70′, for example. Each uniqueidentification code corresponds to a memory location in the readermemory of the reader module 35, which memory location includes at leastone of indexing data, operational data, and tag position data. As anon-limiting example, the tag reader 33 and the reader module 35cooperate to determine vehicle functionality by identifying anindividual tag of the tag layout 50 and associating the identified tagwith a memory location in the reader memory to retrieve at least one ofindexing data, operational data, and tag position data. The individualtags comprise a plurality of zone identification tags 55 and a pluralityof zone tags 60. Each zone identification tag 55 occupies a position inthe tag layout 50 that corresponds to a unique set of zone tags 65 thateach comprise a plurality of zone tags 60. In one embodiment, eachunique set of zone tags 65 comprises a plurality of zone tags 60, one ormore function tags 100, one or more aisle extension tags 110, one ormore aisle entry tags 75, or combinations thereof. For example, and notby way of limitation, respective zone tags 60 of the unique set of zonetags 65 that are the furthest from a midpoint 120 of the aisle path 70of the racking system aisle 70′ may comprise both vehicle functionalityand end-of-aisle vehicle functionality.

As a non-limiting example, the individual tags of the tag layout 50 maycomprise a plurality of aisle entry tags 75 that are positioned along anaisle path 70 between vehicle entry or vehicle exit portions 80 of theaisle path 70. A reader module 35 on the materials handling vehicle 102(FIG. 2 ), an example of which is also described in U.S. Pat. No.9,811,088 assigned to Crown Equipment Corporation, may discriminatebetween the aisle entry tags 75 and the individual tags of the taglayout 50 along the aisle path 70 and correlate end-of-aisle vehiclefunctionality with an identified aisle entry tag 75. A vehiclecontroller may control operational functions of the industrial vehiclehardware of the materials handling vehicle 102 in response to thecorrelation of end-of-aisle vehicle functionality with an identifiedaisle entry tag 75. In this manner, a tag layout 50 can be constructedto comprise aisle entry tags 75 that are positioned within an aisle path70 of the racking system aisle 70′ such that particular end-of-aislevehicle functionality can be implemented as an industrial vehicle 10,traveling within an aisle path 70 of the racking system aisle 70′,approaches the vehicle entry or vehicle exit portion 80 of the aislepath 70. The exit portion distance is a quantity of length measuredbetween a current position of the materials handling vehicle 102 and theend point 85 of respective aisle paths 70. The reader module 35 maydiscriminate between the outer end-cap tag and the inner end-cap tag ofthe end-cap pair 115 and correlate an identified outer end-cap tag withexit-specific vehicle functionality and correlate an identified innerend-cap tag with entry-specific vehicle functionality. In oneembodiment, the tag layout 50 may comprise one or more end-cap rows 117which comprise a plurality of end-cap pairs 115. The one or more end-caprows 117 are spaced across respective end points 85 of an aisle path 70such that an industrial vehicle entering or exiting the aisle path 70will identify the individual tags of the end-cap row 117 regardless ofwhere the materials handling vehicle 102 crosses the end-cap row 117within the vehicle entry or vehicle exit portion 80 of the aisle path70.

The materials handling vehicle 102 can further comprise a rack legimaging module 300 including a camera 304 (FIG. 2 ) for capturing imagessuch as input images of rack leg features. The camera 304 can be anydevice capable of capturing the visual appearance of an object andtransforming the visual appearance into an image. Accordingly, thecamera 304 can comprise an image sensor such as, for example, a chargecoupled device, complementary metal-oxide-semiconductor sensor, orfunctional equivalents thereof. In some embodiments, the materialshandling vehicle 102 can be located within the warehouse 11 and beconfigured to capture images of a rack leg 408 of an upright rail 406 ofa rack 400 in the warehouse 11. In order to capture rack leg images, thecamera 304 can be mounted to at least one lateral side 208 of thematerials handling vehicle 102 and have a field of view laterallyfocused toward the rack leg 408, as described in greater detail below.For the purpose of defining and describing the present disclosure, theterm “image” as used herein can mean a representation of the appearanceof a detected object. The image can be provided in a variety of machinereadable representations such as, for example, JPEG, JPEG 2000, Exif,TIFF, raw image formats, GIF, BMP, PNG, Netpbm format, WEBP, rasterformats, vector formats, or any other format suitable for capturing rackleg uprights.

The materials handling vehicle 102 includes a vehicle body 104. Thevehicle body 104 may include a fork side 202 and a power unit side 204.In embodiments, the fork side 202 may define a front of the materialshandling vehicle 102 configured to move in a forward direction along aninventory transit surface 106 that is horizontally-oriented, and thepower unit side 204 may define a rear of the materials handling vehicle102 configured to move in a reverse direction along the inventorytransit surface 106. The fork side 202 may include a pair of fork tines83. In embodiments, the vehicle body 104 may include a fork carriageassembly 206 positioned at the fork side 202 that may be movably coupledto a mast assembly 207. The fork carriage assembly 206 may be verticallymovable along the mast assembly 207 to retrieve or deposit a tote 50′with respect to a rack 400, which may be a multilevel rack in a verynarrow aisle (VNA) warehouse. The materials handling vehicle 102 mayinclude a sensor location on the fork side 202, the power unit side 204,or both to facilitate autonomous or semiautonomous vehicle travel. Thematerials handling vehicle 102 may also comprise an operator compartment211 that may also be movably coupled to the mast assembly 207. Thisoperator compartment 211 may be positioned between the fork carriageassembly 206 and the power unit side 204 of the vehicle body 104. Thevehicle body 104 may also include a pair of lateral sides 208 extendingbetween the fork side 202 and the power unit side 204 of the vehiclebody 104. The pair of lateral sides 208 thus extend between the frontand rear of the materials handling vehicle 102. The pair of lateralsides 208 may define a width W₁. In VNA environments, a warehouse aislesuch as a racking system aisle 70′ in which the materials handlingvehicle 102 may be positioned may be characterized by an aisle width W₂,where W₂−W₁<W inches and W is in a range of from about 2 inches to about4 inches (and W₂>W₁).

The embodiments described herein can comprise a system 500 including oneor more vehicular processors such as processors 502 (FIG. 4 )communicatively coupled to the camera 304 and a memory. In embodiments,the processors 502 may include a vehicle position calibration processor,a vehicle position processor, a mast assembly control unit, and/or animage capture processor. A network interface hardware 512 may facilitatecommunications over a network 514 via wires, a wide area network, alocal area network, a personal area network, a cellular network, asatellite network, and the like. Suitable personal area networks mayinclude wireless technologies such as, for example, IrDA, Bluetooth,Wireless USB, Z-Wave, ZigBee, and/or other near field communicationprotocols. Suitable personal area networks may similarly include wiredcomputer buses such as, for example, USB and FireWire. Suitable cellularnetworks include, but are not limited to, technologies such as LTE,WiMAX, UMTS, CDMA, and GSM. The network interface hardware 512 can becommunicatively coupled to any device capable of transmitting and/orreceiving data via the network 514. Accordingly, the network interfacehardware 512 can include a communication transceiver for sending and/orreceiving any wired or wireless communication. For example, the networkinterface hardware 512 may include an antenna, a modem, LAN port, Wi-Ficard, WiMax card, mobile communications hardware, near-fieldcommunication hardware, satellite communication hardware and/or anywired or wireless hardware for communicating with other networks and/ordevices.

The one or more processors 502 can execute machine readable instructionsto implement any of the methods or functions described hereinautomatically. Memory as at least one of non-volatile memory 508 orvolatile memory 510 in a computer readable medium 516 (e.g., memory) forstoring machine readable instructions can be communicatively coupled tothe one or more processors 502, the camera 304, or any combinationthereof. The one or more processors 502 can comprise a processor, anintegrated circuit, a microchip, a computer, or any other computingdevice capable of executing machine readable instructions or that hasbeen configured to execute functions in a manner analogous to machinereadable instructions. The computer readable medium 516 can compriseRAM, ROM, a flash memory, a hard drive, or any non-transitory devicecapable of storing machine readable instructions.

The one or more processors 502 and the memory may be integral with thecamera 304. Alternatively or additionally, each of the one or moreprocessors 502 and the memory can be integral with the materialshandling vehicle 102. Moreover, each of the one or more processors 502and the memory can be separated from the materials handling vehicle 102and the camera 304. For example, a management server, server, or amobile computing device can comprise the one or more processors 502, thememory, or both. It is noted that the one or more processors 502, thememory, and the camera 304 may be discrete components communicativelycoupled with one another without departing from the scope of the presentdisclosure. Accordingly, in some embodiments, components of the one ormore processors 502, components of the memory, and components of thecamera 304 can be physically separated from one another. The phrase“communicatively coupled,” as used herein, means that components arecapable of exchanging data signals with one another such as, forexample, electrical signals via conductive medium, electromagneticsignals via air, optical signals via optical waveguides, or the like.

Thus, embodiments of the present disclosure may comprise logic or analgorithm written in any programming language of any generation (e.g.,1GL, 2GL, 3GL, 4GL, or 5GL). The logic or an algorithm can be written asmachine language that may be directly executed by the processor, orassembly language, object-oriented programming (OOP), scriptinglanguages, microcode, etc., that may be compiled or assembled intomachine readable instructions and stored on a machine readable mediumsuch as computer readable medium 516. Alternatively or additionally, thelogic or algorithm may be written in a hardware description language(HDL). Further, the logic or algorithm can be implemented via either afield-programmable gate array (FPGA) configuration or anapplication-specific integrated circuit (ASIC), or their equivalents.

In embodiments, one or more warehouse maps 30 described herein may bestored in the memory. The system 500 can include one or more displaysand/or output devices 504 such as monitors, speakers, headphones,projectors, wearable-displays, holographic displays, and/or printers,for example. Output devices 504 may be configured to output audio,visual, and/or tactile signals and may further include, for example,audio speakers, devices that emit energy (radio, microwave, infrared,visible light, ultraviolet, x-ray and gamma ray), electronic outputdevices (Wi-Fi, radar, laser, etc.), audio (of any frequency), etc.

The system 500 may further include one or more input devices 506 whichcan include, by way of example, any type of mouse, keyboard, disk/mediadrive, memory stick/thumb-drive, memory card, pen, touch-input device,biometric scanner, voice/auditory input device, motion-detector, camera,scale, and the like. Input devices 506 may further include cameras (withor without audio recording), such as digital and/or analog cameras,still cameras, video cameras, thermal imaging cameras, infrared cameras,cameras with a charge-couple display, night-vision cameras, threedimensional cameras, webcams, audio recorders, and the like. Forexample, an input device 506 may include the camera 304 describedherein. As a non-limiting example, the input device 506 may becommunicatively coupled to a rack leg imaging module system 28 includingthe camera 304 of the rack leg imaging module 300 as described herein.

Referring to FIG. 5 , the rack leg imaging module system 28 includescommunicatively coupled components including, but not limited to, anodometry module 29, a hardware control box 34, a control module 36, aninfrared (IR) illumination module 38, an IR camera module 40, a battery32, a vehicle controller 502A, and a yaw rate sensor 31. The IRillumination module 38 and IR camera module 40 in combination arereferenceable to as an IR Camera and IR Illumination Module 41, forminga rack leg imaging module to operate as, for example, the rack legimaging module 300. As will be described in greater detail below, theone or more IR Camera and IR Illumination Modules described herein mayinclude the IR camera module 40 communicatively coupled to the camera304 of the rack leg imaging module 300 and the IR illumination module 38communicatively coupled to the plurality of illuminators 306 of the rackleg imaging module 300 as described herein. In embodiments, the battery32 may be a vehicle battery of the materials handling vehicle 102 or aseparate battery dedicated to the rack leg imaging module system 28. Thehardware control box 34 may include an internal layout with a lightemitting diode (LED) driver to regulate electrical current to aplurality of LEDs as a plurality of illuminators 306, a microcontrollerto count ticks of the odometry module 29, and a DC-DC converter to powerthe camera 304. The odometry module 29 may be any conventional or yet tobe developed odometry module configured to generate materials handlingvehicle odometry data, such as via a wheel encoder of the materialshandling vehicle 102.

The encoder 29 may be a drive wheel encoder or a load wheel encoder ofthe vehicle 102. The drive wheel encoder of the vehicle 102 may beassociated with wheels of the vehicle 102 that move the vehicle 102 onthe inventory transit surface and may be powered by a vehicle motor. Theload wheel encoder may be an encoder associated with the wheel disposednear the fork carriage assembly 206 that follow the motion of thevehicle 102 and provide for less slip. The encoder 29, such as when aload wheel encoder, may be powered by a single one of the modules 51,61. In FIG. 5 , the encoder 29 as a load wheel encoder may be powered bythe IR Camera and IR Illumination Module 41. The encoder 29 may provideencoder/quadrature data to the IR Camera and IR Illumination Module 41.The IR Camera and IR Illumination Module 41 generates and outputs imageinformation sent to the control module 36 that, along with tickinformation as distances between racks, generates a position of thevehicle 102 as described herein based on the images and tickinformation.

The control module 36 is communicatively coupled to the vehiclecontroller 502A, such as a vehicle control area network bus (“CAN bus”)controller. The CAN bus controller incorporates a robust vehicle busstandard to allow microcontrollers and vehicle devices to communicatewithin the vehicle systems without a host computer. The CAN buscontroller incorporates a message-based protocol that cooperates withmultiplex electrical wiring within the vehicle 102. Further, the CAN buscontroller is configured to permit interaction between various vehiclesystems to allow for a wide range of functionality and control throughuse of software rather than hard wiring between such systems. By way ofexample, and not as a limitation, a vehicle subsystem may controlactuators or receive feedback from sensors through the CAN buscontroller to control a vehicle functionality. The CAN bus is configureto collate various sensor inputs from one or more different vehiclesubsystems as needed to determine whether to enact a vehiclefunctionality of the vehicle subsystem based on those sensor inputs.

The vehicle controller 502A is configured to send vehicle informationsuch as a steer wheel angle, a steer wheel speed, and a wire guidancestate to the control module 36, which generates a position of thevehicle 102 based on the received vehicle information, images, and tickinformation and sends the position of the vehicle 102 to the vehiclecontroller 502A.

The IR illumination module 38 may comprise the plurality of illuminators306 of the rack leg imaging module 300 as described herein, and the IRcamera module 40 may comprise the camera 304 of the rack leg imagingmodule 300 as described herein. As a non-limiting example andembodiment, the rack leg imaging module system 28 includes the rack legimaging module 300 including the camera 304 and the plurality ofilluminators 306, LED drivers including an on/off digital controlconfigured to control the plurality of illuminators 306, an odometrymodule 29, the control module 36, and DC-DC converters to power from thebattery 32 to the connected hardware. The control module 36 isconfigured to trigger image capture by the camera 304, accumulateencoder ticks as described in greater detail below, and report tickinformation to the one or more processors 502 through serialcommunication. The control module 36 may further be configured tooperate in two modes, a QR initialization mode to initialize an initialposition of the materials handling vehicle 102 in an aisle entrance of aracking system aisle 70′ in the warehouse 11 and a position maintenancemode to maintain and update the position of the materials handlingvehicle 102 in the racking system aisle 70′ during travel on theinventory transit surface 106, as described in greater detail below.Modes and parameters of the rack leg imaging module system 28 may be setby sending serial commands to the control module 36, which may operateas one of the one or more processors 502 of the system 500.

The rack leg imaging module system 28 may be communicatively coupled toa controller access network (CAN) bus of the materials handling vehicle102 and may utilize an associated wire guidance or rail guidance signalof the materials handling vehicle 102 for localization. The rack legimaging module system 28 may further make use of CAN odometry dataassociated with the materials handling vehicle 102, and publish theposition to CAN, for automatic positioning system and navigation use.The rack leg imaging module system 28 may operate with the CAN interfaceof the materials handling vehicle 102 to provide rack leg imaging to thematerials handling vehicle 102. The rack leg imaging module system 28may further maintain position of the materials handling vehicle 102 inan onboard memory, even when power of the materials handling vehicle 102is turned off.

As is noted above and referring again to FIG. 4 , the materials handlingvehicle 102 can comprise or be communicatively coupled with the one ormore processors 502. Accordingly, the one or more processors 502 canexecute machine readable instructions to operate or replace the functionof the operator controls. The machine readable instructions can bestored upon the memory. Accordingly, in some embodiments, the materialshandling vehicle 102 can be navigated automatically by the one or moreprocessors 502 executing the machine readable instructions. In someembodiments, the location of the vehicle can be monitored by thelocalization system as the materials handling vehicle 102 is navigated.

For example, the materials handling vehicle 102 can automaticallynavigate along the inventory transit surface 106 of the warehouse 11along a desired path to a desired position based upon a localizedposition of the materials handling vehicle 102. In some embodiments, thematerials handling vehicle 102 can determine the localized position ofthe materials handling vehicle 102 with respect to the warehouse 11. Thedetermination of the localized position of the materials handlingvehicle 102 can be performed by comparing image data to map data. Themap data can be stored locally in the memory as one or more warehousemaps 30, which can be updated periodically, or map data provided by aserver or the like. In embodiments, an industrial facility map comprisesa mapping of the racking system features, such as each end rack leg 408of each upright rail 406 of a rack 400 of the racking system 12 at eachaisle end, where each end rack leg 408 is associated with a unique code,including but not limited to codes such as QR codes on aisle entryidentifiers 302 including rack leg identification information asdescribed herein. Given the localized position and the desired position,a travel path can be determined for the materials handling vehicle 102.Once the travel path is known, the materials handling vehicle 102 cantravel along the travel path to navigate the inventory transit surface106 of the warehouse 11. Specifically, the one or more processors 502can execute machine readable instructions to perform localization systemfunctions and operate the materials handling vehicle 102. In oneembodiment, the one or more processors 502 can adjust the steering ofthe wheels 210 and control the throttle to cause the materials handlingvehicle 102 to navigate the inventory transit surface 106.

Referring to FIG. 2 , a rack leg imaging module 300 is shown disposed ona lateral side 208 of a materials handling vehicle 102 between the powerunit side 204 and the fork side 202. The rack leg imaging module 300 isfurther shown as including an arrangement of a camera 304 and anillumination module including a plurality of illuminators 306. The rackleg imaging module 300 may include the camera 304 and a verticallyoriented array of infrared (IR) illuminators 306 and an IR bandpassfilter. The vertically-oriented array of IR illuminators may be disposedon at least one of the pair of lateral sides 208 of the materialshandling vehicle 102. The camera 304 may be vertically aligned with thevertically oriented array of IR illuminators 306 and configured tocapture images of at least a portion of a rack leg 408 positioned in aracking system aisle 70′ of a multilevel warehouse racking system 12. Animage capture processor (e.g., of the processors 502) may be configuredto generate a filtered IR rack leg image by coordinating to capture arack leg image of at least a portion of a rack leg 408 with illuminationof the rack leg 408 by the vertically oriented array of IR illuminators306 and with band pass filtering of external warehouse lightingsurrounding the rack leg 408 from the rack leg image using the IRbandpass filter. The vehicle control architecture may be configured tonavigate the materials handling vehicle 102 along the inventory transitsurface 106 using the filtered IR rack leg image.

In an embodiment, the camera 304 may include a lens and the IR bandpassfilter. The lens may be, but is not limited to, a wide angle lens, afish eye lens, a narrow angle lens, or the like. The lens may bedependent on a leg pattern used for a rack leg 408 in the warehouseenvironment 150. The plurality of illuminators 306 of the illuminationmodule may include, but are not limited to, a plurality of LEDs or othertypes of illumination such as incandescent, fluorescent, IR laser diode,and the like. As a non-limiting example, the plurality of illuminators306 of the illumination module may include a vertical series ofdistributed IR LEDs, each including a narrow beam reflector lens. Therack leg imaging module 300 is mounted on at least one lateral side 208of the materials handling vehicle 102 and configured to laterally face arack 400 in first lateral direction, such as when the materials handlingvehicle 102 is on wire guidance or rail guidance on the inventorytransit surface 106 in a racking system aisle 70′ defined by the rack400. The materials handling vehicle 102 may include an opposite rack legimaging module 300 mounted on the opposite lateral side 208 of thematerials handling vehicle 102 and configured to laterally face in asecond lateral direction opposite the first lateral direction anotherrack 400 defining another side of the racking system aisle 70′. Two rackleg imaging modules 300 mounted on opposite lateral sides 208 of thematerials handling vehicle 102 allows both sides of the racking systemaisle 70′ to be utilized for localization, as described in greaterdetail further below.

Along with a unique code associated with a first aisle entry identifier302 and the three-dimensional coordinates of the rack leg 408 associatedwith the first aisle entry identifier 302 to indicate location of therack leg 408 in the warehouse environment based on the map, the patternsfrom an image of the rack leg 408 captured by the rack leg imagingmodule 300 are recorded in a localization feature map for use duringlocalization system operation, as described in greater detail below. Inan embodiment, mapping of the QR codes associated with rack legs 408 ofracks 400 may occur through manual mapping utilizing a laser tool suchas a laser range finder or laser distance meter or other suitablemapping scanning tools. In embodiments, utilized individual tags, suchas RFID tags as described herein, may be mapped utilizing same orsimilar techniques while further using an antenna to identify a locationof the individual tag.

The vehicle location of the materials handling vehicle 102 may beverified and/or made more accurate based on the rack leg imaging module300 as described herein. For a vehicle that is localized but with lowaccuracy, for example, use of the rack leg imaging module 300 and anaisle entry identifier 302 permits an increase in localization accuracyof the materials handling vehicle 102 upon successful detection of theaisle entry identifier 302. The aisle entry identifier 302 is able to beutilized to initialize a vehicle location or verify the predictedvehicle location and to fix the vehicle localization to a high degree ofcertainty. Increased uptime in the length of time a materials handlingvehicle 102 may be localized through the localization system through useof such rack leg imaging modules 300 enhances value of the vehiclelocalization in the uptime and in improving accuracy of thelocalization. By way of example and not as a limitation, uptimeassociated with the materials handling vehicle 102 references the amountof time the materials handling vehicle 102 may be utilized and not lost,turned off, or otherwise not utilized during periods of downtime. Anunknown location of the materials handling vehicle 102 results indisruption of uptime associated with the materials handling vehicle 102resulting in situations such as inhibited work flow and inefficientvehicle navigation and use. As a non-limiting example, the materialshandling vehicle 102 will stop if it becomes lost such that thelocalization is no longer known, navigation could lead to an incorrecttarget or pick up location if the localization is incorrect, and thelike.

The processes of the rack leg imaging module 300 is set forth in greaterdetail in FIG. 6 . The camera 304 and illuminators 306 of the rack legimaging module may capture an image of a rack leg 408 that is digitizedand may have a stored rack leg pattern superimposed on the digitizedimage to match the image with a stored rack leg 408.

Referring to FIG. 6 , the system 500 through rack leg imaging modulesystem 28 and the camera 304 of the rack leg imaging module 300 isconfigured to provide rack leg imaging for one or more vehicles 102 thatmay be disposed on wire guidance or rail guidance in racking systemaisles 70′ of a warehouse 11. The camera is configured to capture imagesof (i) an aisle entry identifier 302 positioned to correspond with anentrance of a racking system aisle 70′ of a multilevel warehouse rackingsystem 12 and (ii) at least a portion of a rack leg 408 positioned inthe racking system aisle 70′. By way of example and not as a limitation,the system 500 is configured to use the camera 304 of the rack legimaging module 300 to read the aisle entry identifier 302 as a uniquecode associated with a first rack leg 408 of a rack 400 at an aisleentrance and use odometry data from an odometry module 29, such as awheel encoder on the materials handling vehicle 102, to keep track of achange in position of the materials handling vehicle 102. The odometrymodule 29 is configured to generate odometry data representing adistance traveled by the materials handling vehicle 102 along theinventory transit surface 106. The camera 304 is used to continue toidentify rack legs 408 that are passed by in the racking system aisle70′ and use of the identifying information to correct any accumulatedencoder error and thus calibrate odometry information and the updatedposition of the materials handling vehicle 102. Parameters associatedwith the system 500 may be split between storage onboard the rack legimaging module 300 and storage within each unique code associated with arack leg 408.

As a non-limiting example, the process 600 follows instructions tocapture image(s) of a rack leg 408 at an aisle entrance of a firstracking system aisle 70′ to initialize a localization position of thematerials handling vehicle 102 in the warehouse 11 with respect to thefirst racking system aisle 70′. As a non-limiting example, the rack leg408 defines at least a portion of a lateral boundary of the rackingsystem aisle 70′ that may be the aisle entrance of the first rackingsystem aisle 70′ and includes an aisle entry identifier 302, which maybe configured as a sticker on the rack leg 408 including the aisle entryidentifier 302 as a unique QR code. The unique QR code may includelocalization information with respect to the rack leg 408 andinformation about rack leg patterns associated with the rack legs 408 ofa rack 400, such as hole patterns, spacing or “tick” patterns betweenrack legs 408 of the rack 400, and the like. A plurality of images arecaptured at a high rate by the camera 304 to read the unique QR code atthe aisle entrance, which includes a stored position of the associatedrack leg 408, and initialize the position of the materials handlingvehicle 102 in the warehouse 11.

Thus, in block 602, the aisle entry identifier 302 is used to generateracking system information indicative of at least (i) a position of aninitial rack leg 408 of the racking system aisle 70′ along the inventorytransit surface 106 and (ii) rack leg spacing in the racking systemaisle 70′. In block 604, the initial position of the materials handlingvehicle 102 along the inventory transit surface 106 is generated usingthe position of the initial rack leg 408 from the racking systeminformation. It is noted that reference herein to a value or parameterthat is “generated” covers calculating, measuring, estimating, or anycombination thereof. The rack leg imaging module 300 may be commissionedwith a known position of the materials handling vehicle 102 such thatthe updated position of the materials handling vehicle 102 is calculatedbased on the retrieved position of the associated rack leg 408. Aposition of the QR code in the captured image(s) may be used for fineadjustment of the position of the materials handling vehicle 102, givenknown camera parameters and optionally a distance of the camera 304 fromthe rack 400 that may assist, for example, with setting one or morecamera parameters based on a the camera distance to capture an optimal,defined image of the rack leg 408.

After initialization in blocks 602-604, the odometry module 29 of thematerials handling vehicle 102 is used to maintain vehicle positionknowledge. In block 606, an odometry-based position of the materialshandling vehicle 102 along the inventory transit surface 106 in theracking system aisle 70′ is generated using the odometry data and theinitial position of the materials handling vehicle 102. In anembodiment, the rack leg imaging module 300 is commissioned with a knowndistance travelled per tick and a polarity or direction of travel. Suchodometry information is used between the rack legs 408 and capturedimages of the rack legs to estimate and maintain vehicle positionknowledge from a previous image capture. As a non-limiting example, alast image capture is a foundation upon which the odometry is baseduntil a new image is captured to become the last image capture tocontinue to maintain the vehicle position knowledge as the materialshandling vehicle 102 advances along the racking system aisle 70′.

In block 608, a subsequent rack leg 408 is detected using a capturedimage of at least a portion of the subsequent rack leg 408. For example,images continue to be captured by the camera 304 as the materialshandling vehicle 102 travels along the racking system aisle 70′ definedby the rack 400 to detect the plurality of rack legs 408 of the rack 400defining the racking system aisle 70′. Images may be captured by thecamera 304 at a high rate as the materials handling vehicle 102 travelsalong the racking system aisle 70′ defined by a rack 400 and including aplurality of rack legs 408. In embodiments, the images may be capturedby the camera 304 when the rack leg imaging module 300 expects a rackleg 408 to be in the frame. For example, the camera 304 may be triggeredto take an image at a position where a rack leg 408 is expected toappear in the image, which may reduce image processing requirements andcamera interface bandwidth requirements as well as power usage.

In block 610, the detected subsequent rack leg 408 is correlated with anexpected position of the materials handling vehicle 102 in the rackingsystem aisle 70′ using rack leg spacing from the racking systeminformation. As a non-limiting example, such data associated with anexpected position of the rack leg 408 and thus associated with anexpected position of the materials handling vehicle 102 when at the rackleg 408 may be based on information from the unique code, such as the QRcode of the aisle entry identifier 302 and/or the RFID tag of the taglayout 50. Such data may include information of when to trigger asubsequent image capture to capture an image of a subsequent expectedrack leg 408 as a next expected data point. A tolerance with respect tothat next expected data point may be included as well before and afterthe data point. In an embodiment, an expected position may be calculatedby adding a distance between rack legs 408 in a racking system aisle 70′defined by a rack 400 in units of ticks to a previous number of ticksassociated with when the last rack leg 408 was detected. The previousnumber of ticks may be corrected for offset of the rack leg 408 in theimage. The camera 304 and the plurality of illuminators 306 may then betriggered to light and capture an image 450 to detect an expected rackleg 408 when the number of ticks hits a target tick count thresholdnumber.

Referring to FIG. 3 , an image 450 is captured by the camera 304 to showa detected rack leg 408. Circles 452 are disposed on detected holes ofthe detected rack leg 408, and an expected dot pattern 454 is matched tothose detected holes of the rack leg 408 to generate a best-fitcenterline 456. In such embodiments, such features of a rack leg 408 ofa rack 400 in the image 450 may be used as features to detect andidentify the rack leg 408 due to a common hole pattern distinguished bya computer vision system of the camera 304 and the rack leg imagingmodule 300 and a pre-identified spacing between the rack legs 408 of therack 400, which information may be included in the aisle entryidentifier 302 of the first rack leg 408 of a racking system aisle 70′defined by the rack 400 of the multilevel warehouse racking system 12.Use of the plurality of illuminators 306 configured to provide flashillumination and the camera 304 configured to capture images with shortexposure times using, for example, a global shutter camera, allows forfeatures of the detected rack leg 408 to be captured and identified inthe image 450. Further, such a combination of illumination and imagecapture provides a high contrast image such as the image 450 throughillumination of an image foreground and providing a sharp image throughprevention of motion blur. Such image characteristics permit imageprocessing that provides reliable and accurate detection of a positionof the detected rack leg 408. The IR illumination module 38 and the IRbandpass filter on the IR camera module 40 of the rack leg imagingmodule system 28 respectively associated with the plurality ofilluminators 306 and the camera 304 of the rack leg imaging module 300operate to permit most of the external lighting extraneous to imagecapture, such as warehouse lighting, to be ignored and filtered out ofthe image 450. Further, in embodiments where the rack legs 408 areunpainted, are light in color, and/or have a glossy paint coating, awidely spaced vertical array of the plurality of illuminators 306 mayoperate to mitigate the specular reflective nature of rack legs 408 todetect a rack leg 408 in an image 450. A process of illuminating a rackleg 408 through the plurality of illuminators 306 for image capture bythe camera 304 of the rack leg imaging module 300 may includeillumination of a large vertical area of the rack leg 408 to generate alarge vertical field of view for the camera 304 due to a short range ofthe camera 304 to the rack 400 to capture a large area of the rack leg408 in the image 450. Further, the rack legs 408 of the rack 400 mayinclude highly reflective material, and a distributed light source asprovided by the plurality of illuminators 306 of the rack leg imagingmodule 300 is configured to mitigate the high reflective nature of therack leg 408 to provide a sharp and reliable image 450 of a detectedrack leg 408.

In the process 600, the odometry-based position of the materialshandling vehicle 102 is compared with the expected position of thematerials handling vehicle 102. In block 612, an odometry error signalis generated based on a difference between the expected position and theodometry-based position. In embodiments indicative of a match betweenthe expected position and the odometry-based position, the odometryerror signal may be zero. In block 614, the odometry-based position ofthe materials handling vehicle 102 is updated using the odometry errorsignal. Thus, the detected rack leg 408 is used to update a position ofthe materials handling vehicle 102. Each frame is processed to detect arack leg 408 and, when the rack leg 408 is detected, the frame isprocessed by a processor 502 of the system 500 to accurately update theposition of the materials handling vehicle 102 to prevent accumulatederror of odometry data from the estimated maintained position of thematerials handling vehicle 102 based on the odometry module 29 fromgrowing at an unbounded rate. The vehicle control architecture isconfigured to navigate the materials handling vehicle 102 along theinventory transit surface 106 using the updated odometry-based position.In embodiments, the vehicle control architecture is configured to trackthe navigation of the materials handling vehicle 102 along the inventorytransit surface 106 of the racking system aisle 70′, navigate thematerials handling vehicle 102 along the inventory transit surface 106in at least a partially automated manner, or both, using the updatedodometry-based position.

In embodiments, through use of detection of rack legs 408 in a givenracking system aisle 70′ to initialize, maintain, and update a positionof the materials handling vehicle 102 in the given racking system aisle70′ as described herein through the rack leg imaging module 300,commissioning of a system 500 to utilize the rack leg imaging module 300involves simple installation and commission. For example, the system 500may only require aisle entry identifiers 302 such as QR code stickers tobe placed at the entrances of each racking system aisle 70′. Further,the system 500 involves a simplified commissioning as information forthe aisle entry identifier 302 is measured on site, input into a mobilecomputer, and printed on a mobile sticker printer to generate a mobilesticker with a unique QR code to be placed on an associated first rackleg 408 for each racking system aisle entrance in the warehouse 11.Thus, warehouse specific information does not need to be stored on anymaterials handling vehicle 102 for the system 500 as described herein tooperate, resulting in a reduction in commissioning time over systems inwhich such warehouse specific information is required to be stored onthe materials handling vehicle 102. Further, a close, predictablespacing of rack legs 408 in a given racking system aisle 70′ relaxesrequirements on the accuracy of the odometry module 29 as there is lessaccumulation of encoder error between closely spaced, predicablefeatures of the rack legs 408 than there might otherwise be for a systemincluding further spaced and manually placed global features, such asRFID tags in a warehouse floor.

The embodiments and systems described herein permit determination andaccurate maintenance of a position of a materials handling vehicle 102with positional accuracy in a racking system aisle 70′ of the warehouse11. Indeed, a combination of use of aisle entry identifiers 302 such asQR codes for position initialization of a materials handling vehicle 102at aisle entrances and subsequent use of existing, regularly spacedfeatures of rack legs 408 for a given racking system aisle 70′ tomaintain an accurate position of the materials handling vehicle 102along the racking system aisle 70′ permits not requiring use of a QRcode on each rack leg 408 to maintain and update vehicle position of amaterials handling vehicle 102 along the given racking system aisle 70′.For example, a given rack 400 for a racking system aisle 70′ may be overa hundred meters long and may have over 40 rack legs 408.

Referring to FIG. 7 , the vehicle 102 includes the fork carriageassembly 206 as a raisable assembly shown in a lower position on themast assembly 207 and an upper, elevated position on the mast assembly207. A mast sway offset of the position of the mast assembly 207 withrespect to a center of the vehicle 102 along a vertical plane is shownbetween the lower position and the upper, elevated position. The mastsway offset of FIG. 7 is shown such that a first, left vertical planeintersecting an interior portion of the fork carriage assembly 206 inthe lower position, such as a fork slot, does not intersect the interiorportion in the upper, elevated position. Rather, a second, rightvertical plane intersects the interior portion in the upper, elevatedposition. The horizontal distance between the first, left verticalplane, and the second, right vertical plane is indicative of the mastsway offset. The horizontal distance indicative of mast sway offset isfurther, in FIG. 7 , indicative of fork displacement due to mast sway,and the rack leg imaging module 300R has a similar displacement as thefork displacement and mast sway offset.

The fork carriage assembly 206 on the fork side 202 includes the rackleg imaging module 300R as described above as the rack leg imagingmodule 300, though labeled with an R to indicate a risible aspect. Therack leg imaging module 300R is placed on the fork carriage assembly 206at a position to approximate a height of the forks. Thus, a verticaldistance between the forks and an inventory transit surface may bedetermined based on the rack leg imaging module. As described in greaterdetail below, the horizontal distance indicative of the mast sway offsetand the vertical distance between the fork and the inventory transitsurface may be used to determine a mast sway offset compensation withrespect to the vehicle 102.

In an embodiment, a position of a fork slot of the vehicle 102 oranother target location of the vehicle 102 as the interior portion levelwith the rack leg imaging module 300R may be recorded at a set distanceaway from a center of the vehicle 102 in a lowest position of the forkcarriage assembly 206. However, as the fork carriage assembly 206 rises,the position of the fork slot and/or the interior portion may changewith respect to the center of the vehicle 102 due to a mast sway offset.Thus, calculations based on the recorded set distance between fork slotand/or the interior portion and the center of the vehicle 102 may be inerror by the amount of the mast sway offset.

In embodiments, at least one rack leg imaging module 300R will beattached to the fork carriage assembly 206 at a height that approximatesa fork height while having an obstructing view to racking. Rack legsdetected by this rack leg imaging module 300R as described herein maycompensate for mast sway through a determination of mast sway offset asdescribed in greater detail below with respect to FIG. 11 . A positionoutput of the vehicle 102 with the mast sway compensation may thus bedetermined by the rack leg imaging module 300R. A second rack legimaging module 300 may be configured to read a QR code as describedherein and may be disposed on the power unit side 204 at a lower, fixedposition on the vehicle 102. The second rack leg imaging module 300 atthe lower position may ensure that the QR codes are observed and mayprovide redundancy to permit the system to reject false positivedetections.

The rack leg imaging module 300R and the second rack leg imaging module300 may be placed on different positions of the vehicle 102 in differentembodiments, as shown in FIGS. 8A-8E, which show a perspective from thepower unit side 204 toward the fork side 202.

FIGS. 8A-8B depict embodiments in which the rack leg imaging module 300Rand the rack leg imaging module 300 are disposed on opposite sides ofthe vehicle 102. FIG. 8A shows a first embodiment including the rack legimaging module 300R on the fork carriage assembly 206 on a first side ofthe vehicle 102 and a lower, fixed rack leg imaging module 300 fixed tothe vehicle 102 on the power unit side 204 on a second side opposite thefirst side of the vehicle 102. The fork carriage assembly 206 israisable with respect to the mast assembly 207 along a direction ofarrow A such that the rack leg imaging module 300R is configured to movealong the direction of arrow A. FIG. 8B depicts a second embodimentincluding the rack leg imaging module 300R on the fork carriage assembly206 on the second side of the vehicle 102 and the lower, fixed rack legimaging module 300 fixed to the vehicle 102 on the power unit side 204on the first side of the vehicle 102. The raised rack leg imaging module300R is configured to provide position output of the vehicle 102 whilethe second rack leg imaging module 300 is configured to initializevehicle position through reading of a QR code as described herein. Thesecond rack leg imaging module 300 is further configured to generate aposition of rack leg imaging module 300 that matches a position of therack leg imaging module 300R within a predetermined threshold. Failureto match the positions within the predetermined threshold may cause therack leg imaging module 300R to error out and the vehicle 102 to take anaction, such as to halt or slow pending operator override.

FIGS. 8C-8D depict embodiments in which the rack leg imaging module 300Rand the rack leg imaging module 300 are disposed on the same side of thevehicle 102. In FIG. 8C, the rack leg imaging module 300R is disposed onthe fork carriage assembly 206 on the first side of the vehicle 102 andthe lower, fixed rack leg imaging module 300 is fixed to the vehicle 102on the power unit side 204 on the first side of the vehicle 102. In FIG.8D, the rack leg imaging module 300R is disposed on the fork carriageassembly 206 on the second side of the vehicle 102 and the lower, fixedrack leg imaging module 300 is fixed to the vehicle 102 on the powerunit side 204 on the second side of the vehicle 102.

In embodiments in which an aisle only has a single side of racking, thelower, fixed rack leg imaging module 300 may be the module relied uponto determine a position output for the vehicle 102 through a position ofthe rack leg imaging module 300 generated as described herein.Alternatively, the rack leg imaging module 300R if on the same side ofthe single side of racking may be used to determine a position outputfor the vehicle 102 through a position of the rack leg imaging module300R generated as described herein.

FIGS. 8E-8F show a perspective of the materials handling vehicle 102from the power unit side 204 toward the fork side 202. In FIG. 8E, afirst rack leg imaging module 300R-A on the fork carriage assembly 206is disposed on the first side of the materials handling vehicle 102 andanother, second rack leg imaging module 300R-B is disposed on the forkcarriage assembly 206 on the second side of the materials handlingvehicle 102.

Referring to FIG. 8E, the materials handling vehicle 102 may include araisable rack leg imaging module 300R-A on the fork carriage assembly206 on a first side of the vehicle 102 and another raisable rack legimaging module 300R-B on the fork carriage assembly 206 on a second sideopposite the first side of the vehicle 102. In such an embodiment inwhich both rack leg imaging modules 300R-A and 300R-B disposed on thevehicle 102 as raisable with the fork carriage assembly 206, the forkcarriage assembly 206 is to be maintained at a height sufficient to reada QR code upon entering an aisle. Position output may be determinedbased on the one of rack leg imaging modules 300R-A, 300R-B that is onthe same side as a target pallet location in the aisle.

Referring to FIG. 8F, the vehicle 102 may include a fixed position rackleg imaging 300A on a power unit assembly of the power unit side 204 ona first side of the vehicle 102 and another fixed rack leg imagingmodule 300B on the power unit assembly on a second side opposite thefirst side of the vehicle 102.

Referring to FIG. 9 , a rack leg imaging module system 28A isillustrated in an embodiment including a pair of rack leg imagingmodules 300, 300R, 300R-A, and/or 300 R-B and a control module 36. Inparticular, the rack leg imaging module system 28A includes an IR Cameraand IR Illumination Module A 51 and an IR Camera and IR IlluminationModule B 61 that operate similar to IR Camera and IR Illumination Module41 described above with respect to FIG. 5 . The two rack leg imagingmodule system of FIG. 9 includes the IR Camera and IR IlluminationModule A 51 and the IR Camera and IR Illumination Module B 61 that arecommunicatively coupled to the control module 36 and the encoder 29.

The encoder 29 may be a drive wheel encoder or a load wheel encoder ofthe vehicle 102. The drive wheel encoder of the vehicle 102 may beassociated with wheels of the vehicle 102 that move the vehicle 102 onthe inventory transit surface and may be powered by a vehicle motor. Theload wheel encoder may be an encoder associated with the wheel disposednear the fork carriage assembly 206 that follow the motion of thevehicle 102 and provide for less slip. The encoder 29, such as when aload wheel encoder, may be powered by a single one of the modules 51,61. In FIG. 9 , the encoder 29 as a load wheel encoder may be powered bythe IR Camera and IR Illumination Module 51. The encoder 29 providesencoder/quadrature data to the modules 51, 61. The modules 51, 61generate and output image information sent to the control module 36that, along with tick information as distances between racks, generatesa position of the vehicle 102 as described herein based on the imagesand tick information. The control module 36 is communicatively coupledto a vehicle controller 502A, such as a vehicle control area network bus(“CAN bus”) controller. The CAN bus controller incorporates a robustvehicle bus standard to allow microcontrollers and vehicle devices tocommunicate within the vehicle systems without a host computer. The CANbus controller incorporates a message-based protocol that cooperateswith multiplex electrical wiring within the vehicle 102. Further, theCAN bus controller is configured to permit interaction between variousvehicle systems to allow for a wide range of functionality and controlthrough use of software rather than hard wiring between such systems. Byway of example, and not as a limitation, a vehicle subsystem may controlactuators or receive feedback from sensors through the CAN buscontroller to control a vehicle functionality. The CAN bus is configuredto collate various sensor inputs from one or more different vehiclesubsystems as needed to determine whether to enact a vehiclefunctionality of the vehicle subsystem based on those sensor inputs.

The vehicle controller 502A is configured to send vehicle informationsuch as a steer wheel angle, a steer wheel speed, and a wire guidancestate to the control module 36, which generates a position of thevehicle 102 based on the received vehicle information, images, and tickinformation and sends the position of the vehicle 102 to the vehiclecontroller 502A. If a failure message is triggered in the control module36, such as when a position generated based on the IR Camera and IRIllumination Module A 51 is outside of a predetermined threshold whencompared to a position generated based on the IR Camera and IRIllumination Module B 61, the failure message is sent to the vehiclecontroller 502A.

Referring to FIG. 10 , a rack leg imaging module system 28B isillustrated in an embodiment including a pair of rack leg imagingmodules 300, 300R, 300R-A, and/or 300 R-B and a pair of control modules36A, 36B. In particular, the rack leg imaging module system 28B includesan IR Camera and IR Illumination Module A 51 and an IR Camera and IRIllumination Module B 61 that operate similar to IR Camera and IRIllumination Module 41 described above with respect to FIG. 5 . The tworack leg imaging module system of FIG. 10 includes the IR Camera and IRIllumination Module A 51 and the IR Camera and IR Illumination Module B61 that are communicatively coupled to a pair of control modules 36A,36B and the encoder 29. The control modules 36A, 36B are communicativelycoupled to the vehicle controller 502A. The modules 51, 61, the encoder29, and the vehicle controller 502A operate as described above withrespect to FIG. 9 .

The control module M 36A is shown as a master control module, and thecontrol module S 36B is shown as a slave control module. In anembodiment in which an aisle only includes a single side of racking,both control modules 36A, 36B may be used with the same one of the IRCamera and IR Illumination Module A 51 or the IR Camera and IRIllumination Module B 61 as indicated by the dashed line in FIG. 10 .Only the control module M 36A as the master control module will generatea position of the vehicle 102 to send to the vehicle controller 502A.

The modules 51, 61 generate and output image information sentrespectively to the control modules 36A, 36B that, along with tickinformation as distances between racks, generates a position of thevehicle 102 as described herein based on the images and tickinformation. The positions of the vehicle 102 from each of the controlmodules 36A, 36B may be received in each of the control modules 36A,36B, processed, and compared to determine if the positions are within apredetermined tolerance of one another to be valid positions.

The positions of the vehicle 102 may be further generated based oninformation received from the vehicle controller 502A. A resultingvehicle position generated by the control module M 36A as the mastercontrol module may be sent to the vehicle controller 502A. Both thecontrol module M 36A and the control module S 36B may send failuremessages to the vehicle controller 502A, such as if the generatedpositions are not within a predetermined tolerance of one another andare determined to be invalid positions.

Mast Sway Compensation

Referring to FIG. 11 , a mast sway offset compensation method 1100 isshown that may use the rack leg imaging module 300R, 300R-A, and/or300R-B of FIGS. 8A-8E and a position module feedback system of FIG. 5 ,FIG. 9 , or FIG. 10 . While the rack leg imaging module 300R isreferenced below, it is to be understood that any of the rack legimaging modules 300R, 300R-A, and/or 300R-B disposed on and raisablethrough the fork carriage assembly 206 may operate to be used by themast sway offset compensation method 1100.

In an embodiment, the method 1100 may be used for localizing a materialshandling vehicle 102 comprising a camera 304, a mast assembly 207, amast assembly control unit, a fork carriage assembly 206, a vehicleposition processor, and a drive mechanism configured to move thematerials handling vehicle along an inventory transit surface of awarehouse 11. The mast assembly 207 and the mast assembly control unitmay be configured to move the fork carriage assembly along a verticallift axis. The camera 304 may be secured to the fork carriage assembly206. The camera 304 may be secured directly or indirectly to the forkcarriage assembly. The camera 304 is configured to capture (i) a forksdown image of at least a portion of a rack leg 408 positioned in aracking system aisle 70′ of the multilevel warehouse racking system 12,and (ii) a forks-up image of at least a portion of a rack leg 408positioned in a racking system aisle 70′ of the multilevel warehouseracking system 12.

“Forks-up” and “forks-down” are relative terms and generally denotecarriage positions that are respectively higher and lower than theother. Generally, a “forks-up” image will be an image taken by thecamera when the carriage has raised the forks to a position to pick orplace items from an elevated storage position in a multilevel warehouseracking system, while a “forks-down” image will be an image taken by thecamera when the forks are at or near floor level. It is contemplated,however, that any pair of carriage positions where one carriage positionis higher than the other will define positions where a “forks-up” imageand a “forks-down” image may be acquired.

The method 1100 includes, via the vehicle position processor, generatinga forks-down coordinate X1 of the camera 304 along a horizontal axisfrom the forks-down image of the rack leg 408. In block 1102, one ormore first rack leg images is captured at a first, lower position asshown in FIG. 7 by the rack leg imaging module 300R as described herein.A forks-down coordinate X1 is determined based on the one or more firstrack leg images. In an embodiment, a stored set distance between therack leg imaging module 300R on the fork carriage assembly 206 as acenter of the materials handling vehicle 102 may be stored in thecontrol module 36. The forks-down coordinate X1 may be used to generatea position of the rack leg imaging module 300R and may further utilizethe stored set distance to generate a position of the center of thematerials handling vehicle 102 based on the position of the rack legimaging module 300R. A generated position of the vehicle 102 may be thegenerated position of the center of the materials handling vehicle 102based on the position of the rack leg imaging module 300R and the setdistance. The position of the rack leg imaging module 300R is generatedbased on the one or more first rack images and the stored set distanceas a position of the camera 304 with reference to the center of thematerials handling vehicle 102. As the optical center of camera 304adjusts as the rack leg imaging module 300R raises along the mastassembly 207 to a raised position, the stored set distance is no longeran accurate distance to utilize. Rather, an offset of the optical centerof the camera 304 with respect to the center of the vehicle 102 in theraised position needs to be determined and applied to the stored setdistance for accuracy, which offset corresponds to a mast sway offset asdescribed below.

The method 1100 includes generating a forks-up coordinate X2 of thecamera 304 along a horizontal axis from a forks-up image of the rack leg408 captured with the fork carriage assembly 206 at a lift height H1. Inblock 1104, one or more second rack leg images is captured at a second,raised position with respect to the first, lower position as shown inFIG. 7 by the rack leg imaging module 300R. A forks-up coordinate X2 isdetermined based on the one or more second rack leg images. The forks-upcoordinate X2 may be used to generate a position of the rack leg imagingmodule 300R and may further utilize the stored set distance to generatea position of the center of the materials handling vehicle 102 based onthe position of the rack leg imaging module 300R. However, at anelevated position, the distance between the rack leg imaging module 300Rand the center of the materials handling vehicle 102 may change from theset distance that is stored due to mast sway of the mast assembly 207.

The method 1100 further includes determining a mast sway offset as adifference between the forks-down coordinate X1 and the forks-upcoordinate X2. In block 1106, for mast sway compensation, a mast swayoffset is determined based on a difference between the forks-downcoordinate X1 and the forks-up coordinate X2. This difference isassociated with the change of distance from the set distance that isstored due to mast sway of the mast assembly 207. Additionalcalculations may be an offset angle between the original set distanceand a mast sway distance using the forks-down coordinate X1 and theforks-up coordinate X2 and determined vertical distances of the forkcarriage assembly 206 with respect to inventory transit surface. Themast sway offset may further be determined based on the offset angle.The forks of the vehicle 102 may also reference the center of thevehicle 102, such that a set fork distance to the vehicle center isstored. As the rack leg imaging module 300R is disposed on the forkcarriage assembly 206 may be in alignment with the forks, forkdisplacement with respect to the center of the vehicle 102 may also bedetermined through determination of the mast sway offset as describedherein.

The method 1100 includes determining a horizontally advanced position ofthe materials handling vehicle 102 with the fork carriage assembly 206at the lift height H1 using the mast sway offset and a subsequentlycaptured forks-up image of at least a portion of a rack leg 408positioned in the racking system aisle 70′. In block 1108, a position ofthe materials handling vehicle 102 is determined based on the forks-upcoordinate X2 and the mast sway offset. The forks-up coordinate X2 maybe used to generate a position of the rack leg imaging module 300R andmay further utilize the stored set distance compensated by the mast swayoffset to generate a position of the center of the materials handlingvehicle 102 based on the position of the rack leg imaging module 300R.Thus, even though at the elevated position the distance between the rackleg imaging module 300R and the center of the vehicle 102 may changefrom the set distance that is stored due to mast sway of the mastassembly 207, the mast sway offset compensates for such a change. Themast sway offset thus compensates for potential mast sway whendetermining a position of the materials handling vehicle 102 with therack leg imaging module 300R in an elevated position on the mastassembly 207.

The camera 304 may be further configured to capture an image of an aisleentry identifier 302 in a multilevel warehouse racking system 12. In anembodiment, the vehicle position processor may be further configured togenerate aisle-specific rack leg spacing data from an image of an aisleentry identifier 302, as captured by the camera 304, and determine thehorizontally advanced position of the materials handling vehicle 102with the fork carriage assembly 206 at the lift height H1 using theaisle-specific rack leg spacing data in addition to the mast sway offsetand the subsequently captured forks-up image.

Alternatively or additionally, the vehicle position processor may beconfigured to generate end-of-aisle positional data and aisle-specificrack leg spacing data from an image of an aisle entry identifier 302, ascaptured by the camera, generate an initial position of the materialshandling vehicle 102 along the inventory transit surface using theend-of-aisle positional data, generate an expected position of thematerials handling vehicle 102 as the vehicle travels down a rackingsystem aisle corresponding to the aisle entry identifier from theend-of-aisle positional data, the aisle-specific rack leg spacing data,and a forks-down image of at least a portion of a rack leg positioned inthe racking system aisle. The vehicle position processor may be furtherconfigured to update the expected position of the materials handlingvehicle as the vehicle travels down the racking system aisle using themast sway offset and the subsequently captured forks-up image of atleast a portion of a rack leg positioned in the racking system aisle.The aisle entry identifier 302 may be disposed on an end rack leg 408 ofthe racking system aisle 70′.

Further, the camera 304 may be configured to capture an image of anaisle end identifier 302 in a multilevel warehouse racking system 12.The aisle end identifier 302 as described herein may be disposed on anaisle end rack leg 408, which may be an end rack leg 408 of the rackingsystem aisle 70′. As will be described in greater detail below regardingend of aisle protection and methods 1200-1300 of FIGS. 12-13 ,respectively, the vehicle position processor may further be configuredto generate end-of-aisle limit data comprising an end-of-aisle limitfrom an image of an aisle end identifier 302, as captured by the camera304, determine whether the materials handling vehicle 102 exceeds theend-of-aisle limit, transmit a limit-based command to the drivemechanism of the materials handling vehicle 102 when an operating stateof the materials handling vehicle 102 exceeds the end-of-aisle limit,initiate a vehicle action based on the limit-based command, the vehicleaction configured to modify operation of the materials handling vehicle102 to a modified operating state within the end-of-aisle limit, andnavigate the materials handling vehicle 102 to exit the racking systemaisle in the modified operating state. The aisle end identifier 302 maybe disposed on an aisle end rack leg 408. The end-of-aisle limit mayinclude a speed limit, a lift height limit, an acceleration limit, adeceleration limit, a lift acceleration limit, a lift decelerationlimit, or combinations thereof. The vehicle position processor may beconfigured to navigate the materials handling vehicle 102 outside of theracking system aisle 70′ in the modified operating state, in anadditional operating state that is within or outside of the end-of-aislelimit, or in a combination of operating states selected therefrom.

In another end of aisle protection embodiment, the camera 304 isconfigured to capture an image of an aisle entry identifier 302 in amultilevel warehouse racking system 12. The vehicle position processormay be configured to generate end-of-aisle limit data comprising anend-of-aisle limit, end-of-aisle positional data, and aisle-specificrack leg spacing data from an image of an aisle entry identifier, ascaptured by the camera 304, generate an initial position of thematerials handling vehicle 102 along the inventory transit surface 106using the end-of-aisle positional data, and generate an expectedposition of the materials handling vehicle as the vehicle travels down aracking system aisle corresponding to the aisle entry identifier fromthe end-of-aisle positional data, the aisle-specific rack leg spacingdata, and the horizontally advanced position. The vehicle positionprocessor may further be configured to determine whether the operatingstate of the materials handling vehicle 102 exceeds the end-of-aislelimit when the expected position of the materials handling vehiclecorresponds to an end of the racking system aisle, transmit alimit-based command to the drive mechanism of the materials handlingvehicle when the operating state of the materials handling vehicle 102exceeds the end-of-aisle limit, initiate a vehicle action based on thelimit-based command, the vehicle action configured to modify operationof the materials handling vehicle 102 to a modified operating statewithin the end-of-aisle limit, and navigate the materials handlingvehicle 102 to exit the racking system aisle 70′ in the modifiedoperating state. The vehicle position processor may be furtherconfigured to generate the expected position of the materials handlingvehicle 102 from an image of at least a portion of a rack leg 408positioned in the racking system aisle 70′.

As will be described in greater detail below regarding out of aislelocalization and methods 1400-1500 of FIGS. 14-15 , respectively, thevehicle position processor may further be configured to generateend-of-aisle positional data and aisle-specific rack leg spacing datafrom an image of an aisle entry identifier 302, as captured by thecamera 304, and generate an initial position of the materials handlingvehicle 102 along the inventory transit surface 106 using theend-of-aisle positional data, generate an expected position of thematerials handling vehicle 102 as the vehicle travels down a rackingsystem aisle corresponding to the aisle entry identifier 302 from theend-of-aisle positional data, the aisle-specific rack leg spacing data,and the horizontally advanced position. In an embodiment, thehorizontally advanced position of the materials handling vehicle 102with the fork carriage assembly 206 at the lift height H1 may bedetermined using aisle-specific rack leg spacing data in addition to themast sway offset and a subsequently captured forks-up image of at leasta portion of a rack leg 408 positioned in the racking system aisle 70′,and the expected position may be updated using the horizontally advancedposition. The vehicle position processor may be configured to navigatethe materials handling vehicle 102 to exit the racking system aisle 70′,and update the expected position of the materials handling vehicle 102using a dead reckoning component of the materials handling vehicle 102when the materials handling vehicle 102 is outside of the racking systemaisle 70′.

In an additional or alternative embodiment, the camera 304 is configuredto capture images comprising an aisle exit identifier 302 for a rackingsystem aisle 70′ of a multilevel warehouse racking system 12, and thevehicle position processor is configured to generate end-of-aislepositional data from an image of an aisle exit identifier 302, ascaptured by the camera 304, generate a vehicle pose of the materialshandling vehicle 102 relative to the aisle exit identifier 302 using theend-of-aisle positional data, and generate an inventory transit surfaceposition of the materials handling vehicle 102 along the inventorytransit surface 106 using the end-of-aisle positional data, the vehiclepose, and the horizontally advanced position. The vehicle positionprocessor may further be configured to navigate the materials handingvehicle 102 to exit the racking system aisle 70′, and update theinventory transit surface position of the materials handling vehicle 102using a tag identifier component of the materials handling vehicle 102when the materials handling vehicle 102 is outside of the racking systemaisle. Out-of-aisle positional data may be generated from a tagidentifier 71, as received by the tag identifier component, and thevehicle pose of the materials handling vehicle 102 relative to the tagidentifier 71 may be updated using the out-of-aisle positional data.

End of Aisle Protection

Referring to FIG. 12 , a vehicle end of aisle limit determination method1200 is shown. In embodiments, end of aisle protection may limit speedof the vehicle 102 when the vehicle is first locked onto a guidance wireunless the vehicle 102 passes and reads an encoded QR code as describedherein to indicate an end of aisle and information specific to thataisle and end of aisle, such as end of aisle limit information. The endof aisle limit information may cause the vehicle processor 502A to senda command to the vehicle 102, such as to protect the vehicle 102 whenentering or leaving an aisle. The command may be, for example, to slowor halt the vehicle 102 or to enable the vehicle 102 to drive at ahigher speed than a current vehicle speed.

With respect to the method 1200, for a materials handling vehicle 102comprising a camera 304, a vehicle position processor, and a drivemechanism configured to move the materials handling vehicle along aninventory transit surface, the camera 304 may be configured to capturean image comprising an aisle end identifier 302 or an aisle entryidentifier 302 for a racking system aisle 70′ of a multilevel warehouseracking system 12. The vehicle position processor may be then configuredto generate end-of-aisle limit data comprising an end-of-aisle limitfrom an image of an aisle end identifier 302 or an aisle entryidentifier 302, as captured by the camera 304.

In block 1202, for instance, one or more images are captured by thecamera 304 of the rack leg imaging module 300, 300A, 300B, 300R-A,and/or 300R-B as the camera 304 passes a QR code at an end of an aisle(e.g., an aisle entrance or end) as described herein. In an embodiment,a speed of the vehicle 102 may be limited when the vehicle 102 firstlocks onto a guidance wire until the rack leg imaging module 300, 300A,300B, 300R-A, and/or 300R-B passes and reads the rack leg identifier 302such as the QR code on a rack leg 408 as described herein at the end ofan aisle. The QR code is configured to be encoded with one or more endof aisle limits for the aisle.

The method 1200 may further determine whether the materials handlingvehicle exceeds the end-of-aisle limit. In block 1204, the methoddetermines whether the vehicle 102 is within the one or more end ofaisle limits for the aisle based on the QR code. The rack leg imagingsystem associated with the rack leg imaging 300 is configured to outputat continuous or predetermined intervals whether the vehicle 102 iswithin the aisle limits or not during the navigation of the vehicle 102through the aisle. Missed messages may be interpreted by a receiver ofthe vehicle 102 to be indicative of the vehicle 102 being outside of theaisle limit.

In an embodiment, responsive to capture of the image of the aisle entryidentifier 302, an initial position is generated of the materialshandling vehicle 102 along the inventory transit surface 106 using theend-of-aisle positional data, and an expected position is generated ofthe materials handling vehicle 102 as the vehicle 102 travels down theracking system aisle 70′ corresponding to the aisle entry identifierfrom the end-of-aisle positional data and the aisle-specific rack legspacing data. The vehicle position processor may be further configuredto generate the expected position of the materials handling vehicle 102from an image of at least a portion of a rack leg 408 positioned in theracking system aisle 70′. When the expected position of the materialshandling vehicle corresponds to an end of the racking system aisle, thevehicle position processor may be configured to determine whether theoperating state of the materials handling vehicle exceeds theend-of-aisle limit in block 1204. In an embodiment, the expectedposition of the materials handling vehicle 102 may be updated using adead reckoning component of the materials handling vehicle 102 when thematerials handling vehicle is outside of the racking system aisle 70, asdescribed in greater detail below with respect to method 1400. Inanother embodiment, as described in greater detail below with respect tomethod 1500, a vehicle pose of the materials handling vehicle relativeto the aisle exit identifier may be generated using the end-of-aislepositional data, an inventory transit surface position of the materialshandling vehicle 102 along the inventory transit surface 106 may begenerated using the end-of-aisle positional data, the vehicle pose, andthe expected position and updated using a tag identifier component ofthe materials handling vehicle 102 when the materials handling vehicle102 is outside of the racking system aisle 70′.

The method 1200 may further initiate a vehicle action based on thelimit-based command, the vehicle action configured to modify operationof the materials handling vehicle 102 to a modified operating statewithin the end-of-aisle limit, and navigate the materials handlingvehicle 102 to exit the racking system aisle 70′ in the modifiedoperating state. In block 1206, for instance, the vehicle 102 may becommanded to take an action when the vehicle 102 is outside of the oneor more end of aisles. For example, such a determination that thevehicle 102 is outside of the aisle limit may cause the vehiclecontroller 502A to take an action to slow or to halt the vehicle 102.

Referring to FIG. 13 , another vehicle end of aisle limit determinationmethod 1300 based on data redundancy is shown. The method 1300 issimilar to the method 1200 except as otherwise noted herein. The methods1200 or 1300 may further be combined with one or more steps of themethods 600, 1100, 1400, and/or 1500 as described herein. In block 1302,one or more images are captured by the camera 304 of the rack legimaging module 300, 300A, 300B, 300R-A, and/or 300R-B as the camera 304passes a QR code at an end of an aisle (e.g., an aisle entrance or end)as described herein. The rack leg imaging module 300, 300A, 300B,300R-A, and/or 300R-B passes and reads the rack leg identifier 302 suchas the QR code on a rack leg 408 as described herein at the end of theaisle, which QR code is configured to be encoded with one or more end ofaisle limits for the aisle. In block 1304, similar to block 1204 of FIG.12 , the method determines whether the vehicle 102 is within the one ormore end of aisle limits for the aisle based on the QR code.

Further, in block 1306, the method conducts one or more data redundancychecks. The method determines whether data accuracy of whether thevehicle 102 is within the one or more end of aisle limits is valid basedon the passage of the one or more data redundancy checks. The one ormore data redundancy checks add redundancy at each layer of the methodemployed to assist with providing a very low probability of failureduring operation of the vehicle 102. The one or more data redundancychecks thus assist with maintaining an accurate and suitable performancelevel for the vehicle 102.

One of the data redundancy checks may include determining whether thecorrect end of aisle limit data associated with an aisle is beingretrieved through sensing a pair of rack leg identifiers 302 that havethe same data. As a non-limiting example, a rack leg 408 may includeboth a rack leg identifier 302 and a rack leg identifier 302A thatinclude the same data. The rack leg identifiers 302, 302A may bevertically arranged QR codes disposed on the same rack leg 408 such thata camera 304 of a rack leg imaging module 300, 300A, 300B, 300R-A,and/or 300R-B is configured to pass and read the rack leg identifiers302, 302A on the rack leg 408 as described herein. If the read rack legidentifiers 302, 302A do not include the same data, the redundancy checkfails.

Another data redundancy check may include determining whether twosources of distance travelled odometry with respect to the vehicle 102are within a tolerance of one another. By way of example, and not as alimitation, the encoder 29 may include both a drive wheel encoder and aload wheel encoder communicatively coupled to the vehicle 102. Odometrydata from each of the drive wheel encoder and the load wheel encoder maybe received and compared in the control module 36, 36A, and 36B and/orthe vehicle controller 502A to determine whether the odometry data fromeach encoder is within a predetermined tolerance. If so, the redundancycheck passes. If not, the redundancy check fails.

Yet another data redundancy check may include determining whether twocameras 304 on opposite sides of the vehicle 102, as shown in FIGS.8E-8F, detect rack legs 408 within a tolerance of each other. As anon-limiting example, camera data from the rack leg imaging modules300R-A, 300R-B (FIG. 8E) or from the rack leg imaging modules 300A, 300B(FIG. 8F) may be captured, received, and compared in the control module36, 36A, and 36B and/or the vehicle controller 502A to determine whetherthe captured rack legs 408 are within a predetermined tolerance. If so,the redundancy check passes. If not, the redundancy check fails.

One other data redundancy check may include determining whether twocontrol modules 36A, 36B generate respective position outputs asdescribed herein that are within a tolerance of each other. The controlmodules 36A, 36B may operate as separate independent modules or as amaster module 36A and a slave module 36B. Only one of control modules36A, 36B may provide power to the encoder 29 when the encoder 29 is aload wheel encoder. As a non-limiting example, a position output fromthe control module M 36A of FIG. 10 may be compared with a positionoutput of the control module S 36B of FIG. 10 . The position output ofeach may come from the same or a different rack leg imaging module 300,300A, 300B, 300R-A, and/or 300R-B. In an embodiment in which the aisleonly includes a single side of racking, both control modules 36A, 36Bmay use the same camera source, as indicated by the dashed line in FIG.10 , and there is a lower tolerance for position jump indicative of achange in position between time steps. By way of example, and not as alimitation, a position jump may occur where a rack leg 408 is detectedin a location that was not expected based on a tick distance and thesystem accordingly adjusts a position of the vehicle 102 within a timestep. A position jump may further be illustrated where a control module36A determines a first rack leg position of a first rack leg 408 in anaisle based on a first rack leg imaging module 300 and a control module36B determine a second rack leg position of a second, opposing rack leg408 in the aisle based on a second, opposing rack leg imaging module 300on the vehicle 102. The position jump may be based on the differencebetween the first rack leg position and the second rack leg position andbe made in an inches per time step increment. A position jump outside ofa tolerance may be indicative of a redundancy check failure.

The position outputs may be received and compared in the control module36A, 36B and/or the vehicle controller 502A to determine whether thegenerated position outputs are within a predetermined tolerance. If so,the redundancy check passes. If not, the redundancy check fails.

In block 1308, the vehicle 102 may be commanded to take an action whenthe vehicle 102 is outside of the one or more end of aisles and/or basedon the failing of the one or more data redundancy checks. For example,such a determination that the vehicle 102 is outside of the aisle limitand/or a failing of a data redundancy check may cause the vehiclecontroller 502A to take an action to slow or to halt the vehicle 102.Based on a determination that the one or more redundancy checks fail,such that the redundancies do not match or do not match within atolerance as described herein, then one or more of the control module36, 36A, and/or 36B may send a fail message and a command to the vehiclecontroller 502A to take the action, such as to halt the vehicle 102.

Out of Aisle Localization

Referring to FIG. 14 , an out of aisle dead reckoning localizationcontinuation method 1400 is shown. In an embodiment of the method 1400,a materials handling vehicle 102 comprises a camera 304, a vehicleposition processor, and a drive mechanism configured to move thematerials handling vehicle 102 along an inventory transit surface 106,and the camera 304 is configured to capture images comprising (i) anaisle entry identifier 302 for a racking system aisle 70′ of amultilevel warehouse racking system 12, and (ii) at least a portion of arack leg 408 positioned in the racking system aisle 70′.

In block 1402, a position of the vehicle 102 is determined at an end ofan aisle as described herein, such as through use of a rack leg imagingmodule 300 to capture images of the rack leg identifiers 302 on racklegs 408 at aisle ends to update a position of the vehicle 102. Forinstance, the vehicle position processor is configured to (i) generateend-of-aisle positional data and aisle-specific rack leg spacing datafrom an image of an aisle entry identifier 302, as captured by thecamera 304, (ii) generate an initial position of the materials handlingvehicle along the inventory transit surface using the end-of-aislepositional data, and (iii) generate an expected position of thematerials handling vehicle as the vehicle travels down a racking systemaisle corresponding to the aisle entry identifier from the end-of-aislepositional data and the aisle-specific rack leg spacing data.

The vehicle position processor may further be configured to navigate thematerials handling vehicle 102 to exit the racking system aisle 70′. Inblock 1404, wired guidance with respect to the vehicle 102 in the aisleis switched off and/or the vehicle leaves a guidance wire to which thevehicle 102 is coupled prior to the vehicle exiting the aisle andentering an out of aisle area of the warehouse 11, such as shown in FIG.1B. In block 1406, the vehicle 102 is advanced into and navigated withinthe out of aisle area of the warehouse 11.

The vehicle position processor may further be configured to update theexpected position of the materials handling vehicle 102 using a deadreckoning component of the materials handling vehicle 102 when thematerials handling vehicle 102 is outside of the racking system aisle70′. In block 1408, for instance, one or more vehicle dead reckoningcomponents are used to maintain, update, and/or determine position ofthe vehicle 102 within the out of aisle area of the warehouse 11. By wayof example, and not as a limitation, after wire guidance is switched offand/or the vehicle 102 leaves a guidance wire, dead reckoning such asthrough vehicle odometry measurements recorded and transmitted by theencoder 29 of FIG. 5 to the control module 36 may be used to maintain aposition of the vehicle 102 in the warehouse 11. Further, data from thevehicle controller 502 such as the steer wheel angle and the steer wheelspeed is transmitted to the control module 36 to be used with theodometry data to determine the position of the vehicle 102 in thewarehouse 11.

The use of a load wheel encoder as the encoder 29 may provide for moreaccurate odometry data as the load wheel encoder suffers less slip thanuse of a drive wheel encoder that is driven by a motor. However, inembodiments, the load wheel encoder cannot be used when the steeringangle of the vehicle 102 is such that the load wheel is stationary. Theload wheel may reference one or more load wheels positioned near theforks of the vehicle 102 to assist with bearing a load of and navigationof the forks, for example. This angle may be, for example, −78 degreesfor load wheel with respect to the vehicle 102. The use of a load wheelencoder may provide for a distance measurement though not necessarily aheading indication. Regardless of the type of the encoder 29 that isused, other dead reckoning components may be used alternatively or inaddition to improve dead reckoning accuracy, saw as the yaw rate sensor31 of FIG. 5 to provide a heading indication and/or to calibrate aheading indication and account for slip. The yaw rate sensor 31 may be agyroscopic device configured to measure an angular velocity of thevehicle 102 around a vertical axis. An angle between a heading of thevehicle 102 and an actual movement direction of the vehicle 102 would bea slip angle related to a yaw rate of the vehicle 102. In embodiments, acamera pointing to the inventory transit surface 106 of the out of aislearea of the warehouse 11 and/or use of RFID tags may additionally oralternatively be used to provide and/or maintain dead reckoning datawith respect to the vehicle 102 in the warehouse 11.

Referring to FIG. 15 , an out of aisle identifier localizationcontinuation method 1500 is shown. As shown in FIG. 1B, one or more outof aisle identifiers 71 may be placed in one or more out of aisle areasof the warehouse 11. The method 1500 may be used in addition to or inalternative of the method 1400. Further, one or more steps of methods1400 and 1500 may be used in addition to or in alternative of the stepsof methods 600, 1100, 1200, and/or 1300 described herein. Referring tothe method 1500, a materials handling vehicle 102 used may comprise acamera 304, a vehicle position processor, and a drive mechanismconfigured to move the materials handling vehicle 102 along an inventorytransit surface 106, and the camera 304 is configured to capture imagescomprising an aisle exit identifier 302 for a racking system aisle 70′of a multilevel warehouse racking system 12.

In an embodiment, end-of-aisle positional data is generated from animage of an aisle exit identifier 302, as captured by the camera 304, avehicle pose of the materials handling vehicle 102 is generated relativeto the aisle exit identifier 302 using the end-of-aisle positional data,and an inventory transit surface position is generated of the materialshandling vehicle 102 along the inventory transit surface 106 using theend-of-aisle positional data and the vehicle pose. The materials handingvehicle 102 is navigated to exit the racking system aisle 70′, and theinventory transit surface position of the materials handling vehicle 102is updated using a tag identifier component of the materials handlingvehicle when the materials handling vehicle is outside of the rackingsystem aisle. Out-of-aisle positional data may be generated from a tagidentifier 71, as received by the tag identifier component, and thevehicle pose of the materials handling vehicle may be updated relativeto the tag identifier 71 using the out-of-aisle positional data.

In block 1502, for instance, one or more images are captured by the rackleg imaging module 300 on the vehicle 102 as described herein to readand process the one or more out of aisle identifiers 71 in the out ofaisle areas of the warehouse 11. The rack leg imaging module 300captures and processes images of one or more out of aisle identifiers 71similar to how the one or more rack leg identifiers 302 are captured andprocessed by the rack leg imaging module 300 on the vehicle 102 asdescribed herein. Thus, in block 1502, a series of images may becaptured of a QR code as an out of aisle tag identifier 71 in an out ofaisle area of the warehouse 11. Such QR codes may be placed as the oneor more out of aisle identifiers 71 in out of aisle areas of thewarehouse 11 within a height range sufficient to be read by the rack legimaging module 300 of the vehicle 102. When the vehicle 102 includingthe rack leg imaging module 300 is navigating an out of aisle area ofthe warehouse, the vehicle 102 may be maintaining a position estimatethrough dead reckoning as determined through the method 1500 of FIG. 1 .Use of the method 1500 through reading of the QR code in the out ofaisle area through the rack leg imaging module 300 as described hereinoperates to calibrate and correct the position estimate of the vehicle102 in the out of aisle area of the warehouse 11.

In block 1504, a pose of the vehicle 102 relative to the out of aisletag identifier 71 is then determined based on the captured images ofblock 1502 and by, for example, the control module 36. For example,multiple observations of the same out of aisle tag identifier 71 (e.g.,QR code) in the out of aisle area permits a distance and heading of thevehicle 102 relative to the out of aisle tag identifier 71 to bedetermined. The multiple observations may permit image capture ofdifferent angles of the camera 304 of the rack leg imaging module 300 ofthe vehicle 102 with respect to the out of aisle tag identifier 71 to becaptured. The multiple image captures at different angles with respectto the out of aisle tag identifier 71 are used to determine a positionof the camera 304 relative to the out of aisle tag identifier 71, andthus the position of the vehicle 102 may be determined based on theposition of the camera 304 relative to the out of aisle tag identifier71.

In embodiments, one or more sensors on the vehicle 102 may determine adistance to the out of aisle tag identifier 71 and/or a wall, such asthrough use of a laser on the vehicle 102 and a reflector on the out ofaisle tag identifier 71 and/or the wall. Thus, even when the vehicle 102is not fixed on a guidewire, a distance measurement of the vehicle withrespect to a component or structure in the warehouse 11 may bedetermined and used to generate the position of the vehicle 102.

Thus, out of aisle positioning error may be constrained over a largearea including one or more out of aisle areas of the warehouse 11. Inblock 1506, the position of the vehicle 102 in the out of aisle area ofthe warehouse 11 is then updated or initialized based on the pose of thevehicle 102 relative to the QR code as the out of aisle tag identifier71 as determined in block 1504. In embodiments, such as when the vehicle102 is not positioned on guidance wire in the out of aisle area, anestimated previous position of the vehicle 102 should be maintained tobe updated by the determined position of the vehicle 102 based on theposition of the camera 304 relative to the out of aisle tag identifier71. Further, such out of aisle localization of the position of thevehicle 102 in the out of aisle area of the warehouse 11 may enable andbe provided as input for vehicle alert systems, such as alerts thevehicle 102 is entering a restricted zone, a speed limited zone, or thelike.

It is contemplated and within the scope of this disclosure that themethods described herein, such as those set forth in FIGS. 6 and 11-14 ,or one or more steps thereof, may be performed in addition to oralternative of one other in one or more combinations.

For the purposes of describing and defining the present disclosure, itis noted that reference herein to a variable being a “function” of or“based on” a parameter or another variable is not intended to denotethat the variable is exclusively a function of the listed parameter orvariable. Rather, reference herein to a variable that is a “function” ofor “based on” a listed parameter is intended to be open ended such thatthe variable may be a function of a single parameter or a plurality ofparameters.

It is also noted that recitations herein of “at least one” component,element, etc., should not be used to create an inference that thealternative use of the articles “a” or “an” should be limited to asingle component, element, etc.

It is noted that recitations herein of a component of the presentdisclosure being “configured” in a particular way, to embody aparticular property, or to function in a particular manner, arestructural recitations, as opposed to recitations of intended use. Morespecifically, the references herein to the manner in which a componentis “configured” denotes an existing physical condition of the componentand, as such, is to be taken as a definite recitation of the structuralcharacteristics of the component.

For the purposes of describing and defining the present disclosure it isnoted that the term “about” is utilized herein to represent the inherentdegree of uncertainty that may be attributed to any quantitativecomparison, value, measurement, or other representation. The term“about” is also utilized herein to represent the degree by which aquantitative representation may vary from a stated reference withoutresulting in a change in the basic function of the subject matter atissue.

Reference herein to subject matter that is generated, or determined,“from” or “using” a particular input should not be read to imply thatthe subject matter is generated or determined using only the particularinput. These transitional terms, i.e., “from” and “using” are open-endedterms. Accordingly, the use of phrases like “generated from,” “generatedusing,” “determined from,” “determined using,” “updated using,” etc.,are open-ended phrases that contemplate the use of additionalinformation, data, or other input, to further enhance the generation ordetermination. For example, the vehicle position processor of thepresent disclosure is recited herein to generate end-of-aisle positionaldata from an image of an aisle entry identifier, but this recitationshould not be read to exclude the use of other information, likeodometry data or predetermined positional data, to help generateend-of-aisle positional data.

Having described the subject matter of the present disclosure in detailand by reference to specific embodiments thereof, it is noted that thevarious details disclosed herein should not be taken to imply that thesedetails relate to elements that are essential components of the variousembodiments described herein, even in cases where a particular elementis illustrated in each of the drawings that accompany the presentdescription. Further, it will be apparent that modifications andvariations are possible without departing from the scope of the presentdisclosure, including, but not limited to, embodiments defined in theappended claims. More specifically, although some aspects of the presentdisclosure are identified herein as preferred or particularlyadvantageous, it is contemplated that the present disclosure is notnecessarily limited to these aspects.

What is claimed is:
 1. A materials handling vehicle comprising a camera,a vehicle position processor, and a drive mechanism configured to movethe materials handling vehicle along an inventory transit surface,wherein: the camera is configured to capture images comprising (i) anaisle entry identifier for a racking system aisle of a multilevelwarehouse racking system, and (ii) at least a portion of a rack legpositioned in the racking system aisle; and the vehicle positionprocessor is configured to generate end-of-aisle positional data andaisle-specific rack leg spacing data from an image of an aisle entryidentifier, as captured by the camera, generate an initial position ofthe materials handling vehicle along the inventory transit surface usingthe end-of-aisle positional data, generate an expected position of thematerials handling vehicle as the vehicle travels down a racking systemaisle corresponding to the aisle entry identifier from the end-of-aislepositional data and the aisle-specific rack leg spacing data, navigatethe materials handling vehicle to exit the racking system aisle, andupdate the expected position of the materials handling vehicle using adead reckoning component of the materials handling vehicle when thematerials handling vehicle is outside of the racking system aisle. 2.The materials handling vehicle of claim 1, wherein: the camera isconfigured to capture images comprising an aisle exit identifier for aracking system aisle of a multilevel warehouse racking system; and thevehicle position processor is configured to generate end-of-aislepositional data from an image of an aisle exit identifier, as capturedby the camera, generate a vehicle pose of the materials handling vehiclerelative to the aisle exit identifier using the end-of-aisle positionaldata, generate an inventory transit surface position of the materialshandling vehicle along the inventory transit surface using theend-of-aisle positional data, the vehicle pose, and the expectedposition, navigate the materials handing vehicle to exit the rackingsystem aisle, and update the inventory transit surface position of thematerials handling vehicle using a tag identifier component of thematerials handling vehicle when the materials handling vehicle isoutside of the racking system aisle.
 3. The materials handling vehicleof claim 2, wherein the vehicle position processor is configured togenerate out-of-aisle positional data from a tag identifier, as receivedby the tag identifier component, and update the vehicle pose of thematerials handling vehicle relative to the tag identifier using theout-of-aisle positional data.
 4. The materials handling vehicle of claim1, wherein: the materials handling vehicle further comprises a mastassembly, a mast assembly control unit, and a fork carriage assembly;the mast assembly and the mast assembly control unit are configured tomove the fork carriage assembly along a vertical lift axis; and thecamera is secured to the fork carriage assembly and is configured tocapture (i) a forks down image of at least a portion of a rack legpositioned in a racking system aisle of the multilevel warehouse rackingsystem, and (ii) a forks-up image of at least a portion of a rack legpositioned in a racking system aisle of the multilevel warehouse rackingsystem; and the vehicle position processor is configured to generate aforks-down coordinate X1 of the camera along a horizontal axis from theforks-down image of the rack leg, generate a forks-up coordinate X2 ofthe camera along a horizontal axis from a forks-up image of the rack legcaptured with the fork carriage assembly at a lift height H1, determinea mast sway offset as a difference between the forks-down coordinate X1and the forks-up coordinate X2, determine a horizontally advancedposition of the materials handling vehicle with the fork carriageassembly at the lift height H1 using the mast sway offset and asubsequently captured forks-up image of at least a portion of a rack legpositioned in the racking system aisle, and update the expected positionusing the horizontally advanced position.
 5. The materials handlingvehicle of claim 1, wherein the vehicle position processor is configuredto generate end-of-aisle limit data comprising an end-of-aisle limitfrom the image of the aisle entry identifier, as captured by the camera,determine whether the materials handling vehicle exceeds theend-of-aisle limit, transmit a limit-based command to the drivemechanism of the materials handling vehicle when an operating state ofthe materials handling vehicle exceeds the end-of-aisle limit, initiatea vehicle action based on the limit-based command, the vehicle actionconfigured to modify operation of the materials handling vehicle to amodified operating state within the end-of-aisle limit, and navigate thematerials handling vehicle to exit the racking system aisle in themodified operating state.
 6. The materials handling vehicle of claim 5,wherein the end-of-aisle limit comprises a speed limit, a lift heightlimit, an acceleration limit, a deceleration limit, a lift accelerationlimit, a lift deceleration limit, or combinations thereof.
 7. Thematerials handling vehicle of claim 5, wherein the vehicle positionprocessor is configured to navigate the materials handling vehicleoutside of the racking system aisle in the modified operating state, inan additional operating state that is within or outside of theend-of-aisle limit, or in a combination of operating states selectedtherefrom.
 8. The materials handling vehicle of claim 5, wherein thevehicle position processor is configured to determine whether theoperating state of the materials handling vehicle exceeds theend-of-aisle limit when the expected position of the materials handlingvehicle corresponds to an end of the racking system aisle.
 9. Amaterials handling vehicle comprising a camera, a vehicle positionprocessor, and a drive mechanism configured to move the materialshandling vehicle along an inventory transit surface, wherein: the camerais configured to capture images comprising an aisle exit identifier fora racking system aisle of a multilevel warehouse racking system; and thevehicle position processor is configured to generate end-of-aislepositional data from an image of an aisle exit identifier, as capturedby the camera, generate a vehicle pose of the materials handling vehiclerelative to the aisle exit identifier using the end-of-aisle positionaldata, generate an inventory transit surface position of the materialshandling vehicle along the inventory transit surface using theend-of-aisle positional data and the vehicle pose, navigate thematerials handing vehicle to exit the racking system aisle, and updatethe inventory transit surface position of the materials handling vehicleusing a tag identifier component of the materials handling vehicle whenthe materials handling vehicle is outside of the racking system aisle.10. The materials handling vehicle of claim 9, wherein the vehicleposition processor is configured to generate out-of-aisle positionaldata from a tag identifier, as received by the tag identifier component,and update the vehicle pose of the materials handling vehicle relativeto the tag identifier using the out-of-aisle positional data.
 11. Thematerials handling vehicle of claim 9, wherein the vehicle positionprocessor is further configured to generate the inventory transitsurface position of the materials handling vehicle from an image of atleast a portion of a rack leg positioned in the racking system aisle.12. The materials handling vehicle of claim 9, wherein: the camera isconfigured to capture images comprising (i) an aisle entry identifierfor a racking system aisle of the multilevel warehouse racking system,and (ii) at least a portion of a rack leg positioned in the rackingsystem aisle; and the vehicle position processor is configured togenerate end-of-aisle positional data and aisle-specific rack legspacing data from an image of an aisle entry identifier, as captured bythe camera, generate an initial position of the materials handlingvehicle along the inventory transit surface in a racking system aisleusing the end-of-aisle positional data, generate an expected position ofthe materials handling vehicle as the vehicle travels down the rackingsystem aisle corresponding to the aisle entry identifier from theend-of-aisle positional data and the aisle-specific rack leg spacingdata, and update the inventory transit surface position using theexpected position.
 13. The materials handling vehicle of claim 12,wherein the vehicle position processor is further configured to updatethe inventory transit surface position of the materials handling vehicleusing a dead reckoning component of the materials handling vehicle whenthe materials handling vehicle is outside of the racking system aisle.14. The materials handling vehicle of claim 9, wherein: the materialshandling vehicle further comprises a mast assembly, a mast assemblycontrol unit, and a fork carriage assembly; the mast assembly and themast assembly control unit are configured to move the fork carriageassembly along a vertical lift axis; and the camera is secured to thefork carriage assembly and is configured to capture (i) a forks-downimage of at least a portion of a rack leg positioned in a racking systemaisle of the multilevel warehouse racking system, and (ii) a forks-upimage of at least a portion of a rack leg positioned in a racking systemaisle of the multilevel warehouse racking system; and the vehicleposition processor is configured to generate a forks-down coordinate X1of the camera along a horizontal axis from the forks-down image of therack leg, generate a forks-up coordinate X2 of the camera along ahorizontal axis from a forks-up image of the rack leg captured with thefork carriage assembly at a lift height H1, determine a mast sway offsetas a difference between the forks-down coordinate X1 and the forks-upcoordinate X2, determine a horizontally advanced position of thematerials handling vehicle with the fork carriage assembly at the liftheight H1 using the mast sway offset and a subsequently capturedforks-up image of at least a portion of a rack leg positioned in theracking system aisle, and update the inventory transit surface positionusing the horizontally advanced position.
 15. The materials handlingvehicle of claim 9, wherein the vehicle position processor is configuredto generate end-of-aisle limit data comprising an end-of-aisle limitfrom the image of the aisle exit identifier, as captured by the camera,determine whether the materials handling vehicle exceeds theend-of-aisle limit, transmit a limit-based command to the drivemechanism of the materials handling vehicle when an operating state ofthe materials handling vehicle exceeds the end-of-aisle limit, initiatea vehicle action based on the limit-based command, the vehicle actionconfigured to modify operation of the materials handling vehicle to amodified operating state within the end-of-aisle limit, and navigate thematerials handling vehicle to exit the racking system aisle in themodified operating state.
 16. The materials handling vehicle of claim15, wherein the end-of-aisle limit comprises a speed limit, a liftheight limit, an acceleration limit, a deceleration limit, a liftacceleration limit, a lift deceleration limit, or combinations thereof.17. The materials handling vehicle of claim 15, wherein the vehicleposition processor is configured to navigate the materials handlingvehicle outside of the racking system aisle in the modified operatingstate, in an additional operating state that is within or outside of theend-of-aisle limit, or in a combination of operating states selectedtherefrom.
 18. The materials handling vehicle of claim 9, wherein: thecamera is configured to capture an image comprising an aisle entryidentifier for a racking system aisle of a multilevel warehouse rackingsystem; and the vehicle position processor is configured to generateend-of-aisle limit data comprising an end-of-aisle limit from the imageof the aisle entry identifier, as captured by the camera, determinewhether an operating state of the materials handling vehicle exceeds theend-of-aisle limit when the inventory transit surface position of thematerials handling vehicle corresponds to an end of the racking systemaisle, transmit a limit-based command to the drive mechanism of thematerials handling vehicle when the operating state of the materialshandling vehicle exceeds the end-of-aisle limit, initiate a vehicleaction based on the limit-based command, the vehicle action configuredto modify operation of the materials handling vehicle to a modifiedoperating state within the end-of-aisle limit, and navigate thematerials handling vehicle to exit the racking system aisle in themodified operating state.